Abstract: A fixing device 100 includes a fixing belt 102, a heat source 105, a support member 104, a pressure roller 103, and a reinforcing member 106. The fixing belt 102 has a metal sleeve. The heat source 105 is provided within the fixing belt 102. The support member 104 has a contact surface 104a that is in sliding contact with the inside surface of the fixing belt 102. The pressure roller 103 forms a nip with the bottom surface 104a between which the fixing belt 102 is sandwiched and pressed. The pressure roller 103 drives the fixing belt 102 to rotate. The reinforcing member 106 has a surface contacting the support member 104 on which a plurality of irregularities is formed. The reinforcing member 106 is positioned on a side opposite the support member to the bottom surface 104a, and receives a pressure force applied by the pressure roller 103.