Swine industry has conventionally performed surgical castration of male piglets for preventing boar taint. However, there is a current trend of seeking alternatives to the surgical castration, such as nutritional interventions. This study investigated effect of dietary inulin on boar taint in adipose tissues from entire male (EM) and castrated male (CM) pigs. A total of 26 pigs (EM, n=18; CM, n=8) were divided into four treatment groups: EM pigs fed 0% inulin (EM0) and 3% inulin (EM3), and CM pigs fed 0% inulin (CM0) and 3% inulin (CM3). Fat samples were collected from neck, back and belly after trial termination. The back fat indole concentration was lower in CM3 pigs than in EM0 ones (p<0.05), but did not differ between the groups. The average indole concentration of all adipose tissue was lower in EM3, CM0, and CM3 pigs than in EM0 pigs (p<0.05). The back fat skatole concentration was lower in CM0 and CM3 pigs than in EM0 pigs (p<0.05). Similarly, the average skatole concentration of all adipose tissue and the neck fat skatole concentration were lower in CM3 pigs than in EM0 and EM3 ones (p<0.05). However, androstenone levels in adipose tissues were not affected by inulin. Thus, dietary inulin is partial effect for reducing boar taint in EM pigs and has a positive effect on CM pigs. Our results can be utilized as basic data for developing feeding and management methods to support the welfare of EM pigs and prohibit or limit surgical castration.