A fixing device includes a fixing member, a pressing member and a separating member. The fixing member is provided with a sheet passing region and a non-sheet passing region. The separating member has a separating plate and a restricting piece. The restricting piece is provided with a curving surface on a region including the contacting portion with the non-sheet passing region. The curving surface has a first curving area and a second curving area. The first curving area is provided on a downstream side from the contacting portion in a rotating direction of the fixing member. The second curving area is provided on an upstream side from the contacting portion in the rotating direction of the fixing member. The second curving area has a radius of curvature larger than that of the first curving area.