A fixing device includes a fixing roller, a pressure roller, a first bearing, a second bearing, and an annular insulating member. The insulating member is interposed at least one of between the first bearing and a shaft of the fixing roller and between the second bearing and a shaft of the pressure roller. The insulating member has a slit formed in at least one circumferential location thereon and creating a circumferential discontinuity in the insulating member, and includes a projection projecting from one of circumferentially opposed end surfaces of the slit toward the other of the circumferentially opposed end surfaces.