Heater and inkjet printer

An inkjet printer comprising:

• each of a plurality of ink holders that holds each of a plurality of different colors of ink;
• each of a plurality of planar heat generators that is provided on each of the plurality of ink holders and heats each of the plurality of ink holders;
• each of a plurality of power supply circuits that controls supply of power to each of the plurality of planar heat generators;
• each of a plurality of temperature sensors that is provided on each of the plurality of planar heat generators and measures a temperature;
• and
• a hardware processor that detects abnormality of the temperature sensor in a case where a difference in temperature measured by each of two of the temperature sensors out of the plurality of temperature sensors exceeds an abnormality threshold value after a predetermined waiting time has elapsed since the supply of power to each of the plurality of planar heat generators is stopped.