Uwamuki Kuroko is the most typical kuroko-type deposit in Japan. It is located in the aborted island-arc rift zone formed in the Miocene epoch and is hosted in the felsic volcanic package within a bimodal (basalt-rhy-olite) sequence. The Uwamuki deposit consists of underlying pipe-like siliceous ore and layered massive black ore, showing vertical metal zoning from yellow ore upwards to black ore. In order to study the sources of ore-forming metals, which is a long debated and unsolved issue, Re-Os isotope and He isotope compositions of the ore and host rock were systematically analyzed. The rhyolites hosting the siliceous ore yield R/Ra ratios ranging from 0. 93 to 1. 14, suggesting that the felsic magma should be mainly formed by remelting of the continental crust. The massive black ores have relatively high 187Os/188Os ratios (2. 246 - 7. 608), showing the Os came from either crust-derived sediments or underlying basement rocks in the ore district. The stringer or stockwork siliceous ore and massive yellow ore as well as occasional black ore yield relatively low 187Os/188Os ratios (0. 432 -0. 793), indicating that the ore Os has two possible sources, i. e. mantle and continental crust, which contributed about 57%-89% of mantle Os and 11%-43% of crust Os to the Uwamuki deposit, respectively. A clear vertical rhythmic variation of 187Os/188Os ratios in the layered massive black ore has been observed, which suggests the periodically mixing among ore-forming fluids (metals) in various stages. Based on the fluid mixing and metal sources, a new two-stage model is proposed to illustrate ore-forming processes of the Uwamuki kuroko deposit.