A torsion coil spring biasing and rotating a drive gear of a valve device in one direction and defining a rotation position of a valve body when an electric motor is not operating is included, one end of the torsion coil spring is locked at any one of two locking portions provided at the drive gear, the other end is locked at a casing rotatably supporting the valve shaft, the drive gear is a plate-shaped members including two locking portions and formed linearly symmetrically, the locking portions are formed into hook shapes including extending portions extending in a direction away from an inner surface of the drive gear and distal end portions projecting along the inner surface from distal ends of the extending portions. The drive gear includes openings at positions at which the openings overlap the distal end portions in a view in a direction of the axial line.