A valve device includes: a housing having an inner peripheral wall defining a cylindrical space therein; a fluid introduction path formed in the housing to communicate with the cylindrical space; fluid discharge paths formed in the housing to communicate with the cylindrical space; a valve body accommodated in the cylindrical space and formed of a spherical body having a communication path communicating the fluid introduction path with at least one of the fluid discharge paths; a valve body rotating mechanism rotating the valve body about an axis of the cylindrical space; a protrusion protruding from the inner peripheral wall toward the axis of the cylindrical space to surround at least a portion of an opening in the fluid introduction path; and a seal member provided on the protrusion and capable of abutting on the valve body.