A throttle valve device ideal for small, inexpensive implements is provided. The throttle valve device having a damping member for slowly closing a throttle valve. The throttle valve device (1) has a throttle valve (4) that is fixed to a throttle shaft (5) pivotably supported in an air intake passage (2) and that is urged towards the closed direction, the throttle valve (4) adapted for adjusting the amount of air passing through the air intake passage (2). A through-bore (31) penetrating a shaft bore of the throttle shaft (5) is formed in a body, and a damping member (8) having frictional capabilities is inserted into and supported in the through-bore (31) in a state of pressing against the throttle shaft (5) inserted through the shaft bore (51).