To evaluate the arsenic effect of fish endocrine disruption, crucian carp (Carassius auratus) were treated with 0.5 mg/L and 3.0 mg/L of As$_2$O$_3$ for 14 days and gonadal development was examined by histological analysis. In ovaries from female crucial carps exposed to 3.0 mg/L, immature follicles and atretic follicles were appeared while various normal developmental stages of oocytes were shown in control group. Body weight and Gonadosomatic Index (GSI) of treated carp were also decreased compared to control group. However, no other significant histological changes in liver or kidney were shown in this exposure scheme. This means that reproductive organs are more sensitive than other organs and arsenic may exert endocrine disrupting effect through inhibiting the development of reproductive organ in fish.