To move a fusing belt smoothly, and to convey a recording medium smoothly, a fusing device according to this invention has a belt, a pressure member disposed in contact with the belt, and a pushing member disposed inside the belt, pushing the belt. Where a friction coefficient of an inner circumferential surface of the belt is set to .mu..sub.i, a friction coefficient of a transit area for a recording medium on an outer circumferential surface of the belt is set to .mu..sub.01, and where a friction coefficient of a non-transit area for the recording medium on the outer circumferential surface of the belt, having a friction coefficient rendered larger than the friction coefficient .mu..sub.0i, is set to .mu..sub.02, a relation of .mu..sub.01<.mu..sub.i<.mu..sub.02 is satisfied. Therefore, even where the recording medium having a small friction coefficient is used, or where the pressure member having mold releasing property is used, moving force for moving the belt and conveyance for conveying the recording medium can be increased.