In order to help the marketers of the men`s casual wear brands establish the marketing strategies to their target consumers, it is the purpose of this study to investigate on the variables affecting the casual wear purchase behavior of men in twenties, thirties and forties, and to clarify the differences of casual wear purchase behavior according to their age, The subjects were 429 men in their twenties, thirties and forties living in Seoul and data were analyzed by frequency, percentage, mean and standard deviation, x², ANOVA and Duncan`s test. The results were as follows : (1) Significant differences were found among men in twenties, thirties and forties according to the self-image. Men in forties favored the conservative and not-noticeable image of casual wear, however, men in twenties and thirties favored those of the active, sexy, and distinctive image. (2) Significant differences were found among men in twenties, thirties and forties according to the importance of the store attributes such as convenience of transportation and parking place, clothing in vogue, and various merchandise. Men in thirties and forties put more importance on convenience of transportation and parking place. Men in forties put more importance on various merchandise than men in twenties and thirties. (3) Significant differences were found among men in twenties, thirties and forties according to general purchase behavior of casual wear. * Differences of the use of information according to age Majority of the men consulted the T.V., radio and people in their boundaries * Differences of the clothing purchase frequency according to age Men in twenties buy more clothing than other age groups. Men in twenties buy the clothing every one month and every three months and men in thirties and forties buy the clothing every three months and every six months. * Differences of the shopping day according to age Majority of the men buy the clothing on Saturday and Sunday. However men in twenties buy the clothing more on weekdays than other age groups. * Differences of the shopping place according There were not significant differences among three different age groups and majority of the men found out to utilize the department store. * Differences of the influence of the partners according to age Men in twenties found out to rely on their own decisions but men in thirties and forties found out to depend on their wives(loves). * Differences of the selection standards of casual wear according to age There were not significant differences according to age and adult males found out to select the casual wear by design, quality price in sequence.