To form an amphibious bicycle by adding a slight equipment without basically changing a structure of the conventional bicycle.

A float 1 is provided to be fixed by a side frame set up to a car body in both sides of a bicycle, and a rear part float 3 (float) is provided also in a rear part of the bicycle, and a structure having buoyancy able to perform not only running on the ground but also running on the water is formed. In order to obtain thrust force at water running time, a link mechanism is provided, which performs movement similar to movement of legs of a water bird in the water, by connecting a rotary frame with the side frame serving as the support point and an upper end of a fin mechanism 6 (supported by the frame) by a pin joint.