Hi i just like to add on this tread, i'll copy paste what i have read at Aikidofaq.com
What is a hakama and who wears it?
A hakama is the skirt-like pants that some Aikidoka wear. It is a traditional piece of samurai clothing. The standard gi worn in Aikido as well as in other martial arts such as Judo or Karate was originally underclothes. Wearing it is part of the tradition of (most schools of) Aikido.
The hakama were originally meant to protect a horseman's legs from brush, etc., -- not unlike a cowboy's leather 'chaps'. Leather was hard to come by in Japan, so heavy cloth was used instead. After the samurai as a class dismounted and became more like foot-soldiers, they persisted in wearing horseman's garb because it set them apart and made them easily identifiable.
There were different styles of hakama though. The type worn by today's martial artists - with "legs" - is called a joba hakama, (roughly, horseriding thing into which one steps). A hakama that was kind of like a tube skirt - no legs - another and the third was a very long version of the second. It was worn on visits to the Shogun or Emperor. The thing was about 12-15 feet long and was folded repeatedly and placed between the feet and posterior of the visitor. This necessitated their shikko ("knee walking") for their audience and made it extremely unlikely that they could hide a weapon (retainers suited them up) or rise quickly to make an attack.
The 7 folds in the hakama (5 in the front, 2 in the back) is said to have the following symbolic meaning:
1. Yuki = courage, valor, bravery
2. Jin = humanity, charity, benevolence
3. Gi = justice, righteousness, integrity
4. Rei = etiquette, courtesy, civility (also means bow/obeisance)
5. Makoto = sincerity, honesty, reality
6. Chugi = loyalty, fidelity, devotion
7 .Meiyo = honor, credit, glory; also reputation, dignity, prestige
In many schools, only the black belts wear hakama, in others everyone does. In some places women can start wearing it earlier than men (generally modesty of women is the explanation - remember, a gi was originally underwear).
O Sensei was rather emphatic that EVERYONE wear the hakama, but he came from a time/culture not too far from wearing hakama as standard formal wear.
"Most of the students were too poor to buy a hakama but it was required to wear one. If they couldn't get one from an older relative, they would take the cover off an old futon, cut it, dye it, and give it to a seamstress to make into a hakama.
Since they had to use cheap dye, however, after awhile the colorful pattern of the futon would start to show through and the fluff from the futon would start to work its way out of the material."
Saito Sensei, about hakama in O Sensei's dojo in the old days.
"In postwar Japan many things were hard to get, including cloth. Because of the shortages, we trained without hakama. We tried to make hakama from air-raid blackout curtains but because the curtains had been hanging in the sun for years, theknees turned to dust as soon as we started doing suwariwaza. We were constantly patching these hakama. It was under those conditions that someone came up with a suggestion: "Why don't we just say that it's okay not to wear a hakama until you're shodan?" This idea was put forward as a temporary policy to avoid expense. The idea behind accepting the suggestion had nothing to do with the hakama being a symbol for dan ranking."
Shigenobu Okumura Sensei, "Aikido Today Magazine" #41
"When I was uchi deshi to O Sensei, everyone was required to wear a hakama for practice, beginning with the first time they stepped on the mat. There were no restrictions on the type of hakama you could wear then, so the dojo was a very colorful place. One saw hakama of all sorts, all colors and all qualities, from kendo hakama, to the striped hakama used in Japanese dance, to the costly silk hakama called sendai-hira. I imagine that some beginning student caught the devil for borrowing his grandfather's expensive hakama, meant to be worn only for special occasions and ceremonies, and wearing out its knees in suwariwaza practice.
I vividly remember the day that I forgot my hakama. I was preparing to step on the mat for practice, wearing only my dogi, when O Sensei stopped me. "Where is your hakama?" he demanded sternly. "What makes you think you can receive your teacher's instruction wearing nothing but your underwear? Have you no sense of propriety? You are obviously lacking the attitude and the etiquette necessary in one who pursues budo training. Go sit on the side and watch class!"
This was only the first of many scoldings I was to receive from O Sensei. However, my ignorance on this occasion prompted O Sensei to lecture his uchi deshi after class on the meaning of the hakama. He told us that the hakama was traditional garb for kobudo students and asked if any of us knew the reason for the seven pleats in the hakama.
"They symbolize the seven virtues of budo," O Sensei said. "These are jin (benevolence), gi (honor or justice), rei (courtesy and etiquette), chi (wisdom, intelligence), shin (sincerity), chu (loyalty), and koh (piety). We find these qualities in the distinguished samurai of the past. The hakama prompts us to reflect on the nature of true bushido. Wearing it symbolizes traditions that have been passed down to us from generation to generation. Aikido is born of the bushido spirit of Japan, and in our practice we must strive to polish the seven traditional virtues."
Currently, most Aikido dojo do not follow O Sensei's strict policy about wearing the hakama. Its meaning has degenerated from a symbol of traditional virtue to that of a status symbol for yudansha. I have traveled to many dojo in many nations. In many of the places where only the yudansha wear hakama, the yudansha have lost their humility. They think of the hakama as a prize for display, as the visible symbol of their superiority. This type of attitude makes the ceremony of bowing to O Sensei, with which we begin and end each class, a mockery of his memory and his art.
Worse still, in some dojo, women of kyu rank (and only the women) are required to wear hakama, supposedly to preserve their modesty. To me this is insulting and discriminatory to women Aikidoka. It is also insulting to male Aikidoka, for it assumes a low-mindedness on their part that has no place on the Aikido mat.
To see the hakama put to such petty use saddens me. It may seem a trivial issue to some people, but I remember very well the great importance that O Sensei placed on wearing hakama. I cannot dismiss the significance of this garment, and no one, I think, can dispute the great value of the virtues it symbolizes. In my dojo and its associated schools I encourage all students to wear hakama regardless of their rank or grade. (I do not require it before they have achieved their first grading, since beginners in the United States do not generally have Japanese grandfathers whose hakama they can borrow.) I feel that wearing the hakama and knowing its meaning, helps students to be aware of the spirit of O Sensei and keep alive his vision.
If we can allow the importance of the hakama to fade, perhaps we will begin to allow things fundamental to the spirit of Aikido to slip into oblivion as well. If, on the other hand, we are faithful to O Sensei's wishes regarding our practice dress, our spirits may be more faithful to the dream to which he dedicated his life."
Mitsugi Saotome Sensei, "The Principles Of Aikido"