A collapsible deflector member of a sunroof device including a front portion on the front side of an opening and corner portions extending rearward from the front portion, respectively, a lower edge fixed to a lower edge of the deflector and attached to a fore part of a frame structure, an upper edge supporting an upper edge of the deflector, and arms end connected to one of longitudinal ends of the upper edge in a manner that allows the arm end to move. Upper edges of the front portion and the corner portions of the deflector include a bag-shaped fitting portion fitted onto the upper edge, and in the arm, an arc-shaped portion inserted into the corner portion of the deflector is formed at the arm end, and a connecting portion positioned on an end side of the arc-shaped portion and connected to an end of the upper edge.