Ascorbate oxidase activity in various cucumber tissue extracts was highest in young fruit peeling. Cucumber callus was induced from young fruit peeling and callus cell lines were selected for more than 7 months, which porduced high levels of ascorbate oxidase and had a high growth rate. Induction of callus was optimized with Linsmaier-Skoog(LS) medium at 25$^{circ}C$ in dark phase. Ascorbate oxidase activity reached a maximum at 5 days after transfer to LS basal liquid-medium ant then declined. The enzyme activity in callus cells was stimulated by addition of 10${mu}$M $CuSO_4$ in the early logarithmic phase of growth. And also, adding 10${mu}$M $CuSO_4$ at 3rd day 7th day of culture period, ascorbate oxidase activity in callus cells was maintained to high level. Maximum yield of ascorbate oxidase was found at the 25th day by flask shaking culture, but three-fold of ascorbate oxidase activity was obtained at the 16th day by jar fermentation.