A deflector device includes: a deflector base fixed to side edge portions of a roof opening portion provided in a roof of a vehicle; a deflector arm assembled to the deflector base to extend along the side edge portions and rotatably supported to approach and separate from the roof opening portion in response to an opening and closing operation of a panel for opening and closing the roof opening portion; a deflector unit configured to be deployed when the deflector arm is separated from the roof opening portion and to be stored when the deflector arm approaches the roof opening portion; and a biasing member installed such that one end side thereof is assembled to the deflector base and the other end side thereof biases the deflector arm in a direction in which the deflector arm is separated from the roof opening portion.