A butterfly valve of the present invention comprises holes formed in the side wall of a housing having a fluid passage, bushings pressed into the holes, a shaft of valve body inserted into the bushings to rotatably support the valve body, a step surface facing the upper stream which is formed at a substantially semi-circular portion on the peripheral wall of the fluid passage, and a step surface facing the lower stream which is formed at another substantially semi-circular portion thereon, the peripheral end surfaces of the valve disc being brought into contact with the step surfaces, wherein the shaft is arranged by being offset to the downstream side with respect to the valve disc.