A fixing device, and an image forming method and an image forming apparatus using the fixing device. The fixing device includes an application unit to apply a foam-like fixing agent including a softener to particulates including a resin on a medium, the softener softening the particulates by at least partially dissolving or swelling the resin and a thickness control unit to control a layer thickness of the foam-like fixing agent such that an application time during which the foam-like fixing agent is applied to the particulates is not shorter than a penetration time required for the foam-like fixing agent to penetrate through a layer of the particulates to the medium.