Fixing device, image forming apparatus, and temperature sensor capable of suppressing compression of sheet conveying space and increasing flexibility of cable routing

A fixing device, comprising:

• a fixing member that is mounted to be rotatable and fixes a toner image transferred onto a sheet to the sheet;
• a pressure member that forms a fixing nip portion between the pressure member and the fixing member;
• a heater that is provided to face the pressure member with the fixing member sandwiched therebetween and heats the fixing member;
• a support surface forming portion that is provided separately from the pressure member and the heater and forms a support surface facing the fixing member;
• and
• one or more temperature sensors that is provided on the support surface and detects a temperature of the fixing member,
• the temperature sensor including
• a rectangular substrate,
• a connector that is provided at an end of the substrate on a downstream side in a first direction along one side of the substrate and has a connection portion to which a cable is connected that faces the first direction,
• a temperature detection device that is provided upstream of the connector on the substrate in the first direction and detects the temperature of the fixing member, and
• a pair of through hole portions that is provided on both sides of the temperature detection device in a second direction orthogonal to the first direction and used for positioning the temperature sensor on the support surface.