There are many students who modify their uniforms and wear fashion accessories to pursue their individualities. The objectives of this research were to identify school uniform modification and fashion accessory wearing behavior of high school students. The results were as follows; 1. High school students considered that the uniform was desirable because the uniform showed identity best, but many students complained that the uniform was uncomfortable in activity. The most accessory used for the uniform was the cellular phone handle. 2. The uniform modification behavior was highly distinguishable at the coeducational school, the vocational school, and the art or physical school. They modified their uniform to pursuit slim and individuality. The uniform modification was for the beauty aspect more rather than practical aspect of uniform, and was proportional to the degree of the appearance, and in case of pants, the length and width of the pants showed increasing trend compared to the past. They considered accessory wearing as a compensational expression of the most of students who were not actively behaving on the uniform modification.