Temperature regulator and abnormality determination method capable of more reliably preventing damage to the heater caused by a sensor being deviated from an appropriate measurement position

Provided are a temperature regulator and an abnormality determination method capable of more reliably preventing damage to the heater caused by a sensor being deviated from an appropriate measurement position. A measurement unit measures the temperature of the heater. A calculation unit calculates a control value for controlling the heater based on the measurement temperature measured by the measurement unit and the preset temperature. When the calculation value calculated by the calculation unit exceeds the preset upper limit of the control value, a control unit uses the upper limit of the control value as the control value for output. A detection unit detects that the calculation value calculated by the calculation unit exceeds the upper limit of the control value outputted from the control unit. A measuring unit measures the duration of a state in which the detection unit detects that the calculated value exceeds the upper limit of the control value outputted from the control unit.