To utilize a human leg power, enhance the speed of a vessel, and realize a stable vehicle by providing a feathering paddle wheel mechanism having a large-diameter power transmission means in a position corresponding to the rear wheel of a land bicycle as a propulsion mechanism of a water bicycle.

A handle 2 is fixed to a frame 1 provided with a front-side frame 4 and a rear-side frame 5 and the frame 1 is connected to a pair of floats 15a, 15b. The pair of floats 15a, 15b are provided with a planetary gear 11a and a fixed gear 11b, which are connected by a planetary chain 12a for turning a plurality of paddles 10a, 10b and 10c, 10d in one direction, and are so set to have a large-diameter feathering paddle wheel mechanism provided with the planetary gear lid and the fixed gear 11c connected by the planetary chain 12b attached thereto. This constitution can expand the action range of the vehicle moving on the water using the human power.