A nip formation assembly disposed opposite an opposed rotator via an endless belt includes a nip formation pad to press against the opposed rotator via the endless belt to form a fixing nip between the endless belt and the opposed rotator, through which a recording medium bearing a toner image is conveyed. A fixing heater is disposed opposite at least a center span of the endless belt in an axial direction thereof where the recording medium is conveyed. The fixing heater heats the endless belt. A lateral end heater is mounted on the nip formation pad and disposed opposite a lateral end span of an inner circumferential surface of the endless belt in the axial direction thereof. The lateral end heater heats the endless belt.