A fixing device includes an endless belt that rotates and is heated by a heat source. A thermal conduction aid includes a contact portion, an upstream bent portion, and a downstream bent portion. The contact portion contacts the endless belt. The upstream bent portion and the downstream bent portion are disposed upstream and downstream from the contact portion in a rotation direction of the endless belt, respectively, and are extended in a longitudinal direction of the thermal conduction aid. A recess is disposed in at least one of the upstream bent portion and the downstream bent portion. The recess spans a center of the thermal conduction aid in the longitudinal direction thereof and is recessed from an edge of the at least one of the upstream bent portion and the downstream bent portion in a short direction thereof.