Heater and image forming apparatus

A heater, comprising:

• a substrate that has electrical conductivity and extends in a first direction;
• a first insulation portion that is provided on a first surface of the substrate, has an insulation property, and extends in the first direction;
• at least one heat generation body that is provided on the first insulation portion and extends in the first direction;
• a second insulation portion that is provided on a second surface of the substrate which is opposite to the first surface, has an insulation property, and extends in the first direction;
• at least one detection unit that is provided on the first insulation portion;
• and
• a first wiring which is provided on the first insulation portion and extends in the first direction, and in which one end is electrically connected to one terminal of the detection unit and the other end is electrically connected to the substrate having the electrical conductivity,
• the first insulation portion has a hole passing through the first insulation portion in a thickness direction,
• the other end of the first wiring is electrically connected to the substrate through the hole of the first insulation portion, and
• the detection unit is in parallel with the heat generation body in a second direction orthogonal to the first direction, and detects a temperature of the heat generation body.