A fixing device includes a fixing rotator, a heater, a pressure rotator, a stay, a biasing member fixed to the stay, and a nip formation pad. The nip formation pad is supported by the stay, disposed inside the fixing rotator, and forms a nip. The nip formation pad includes at least one engaged portion at a position other than both ends of the nip formation pad or engaged portions at both ends of the nip formation pad. The at least one engaged portion engages an engaging portion in the stay to generate a first rotational moment. The engaged portions at both ends engage engaging portions in the stay to generate a second rotational moment. Each rotational moment is smaller than a rotational moment generated by engagement between an engaging portion in the stay and an engaged portion at only one end of the nip formation pad.