We reported the growth of ZnSe nanowires on oxidized Si substrate by molecular-beam epitaxy. It was found that average length, average diameter, and density of the ZnSe nanowires were 1.2 mu m, 48 nm, and 1.04x10(7) cm(-2), respectively. It was also found that the ZnSe nanowires were structurally uniform and defect-free with a pure zinc blend structure. UV photodetectors were then fabricated by sputtering a thick Au film through an interdigitated shadow mask onto the ZnSe nanowires. It was found that photocurrent to dark current contrast ratio of our ZnSe nanowire photodetector was >90 with 0.1 V applied bias.