Fixing device and image formation apparatus

An image formation apparatus having a fixing device for fixing an unfixed toner image formed on a recording sheet by passing the recording sheet through a fixing nip and applying heat and pressure to the recording sheet,

• the fixing device comprising:
• a heater including a resistance heater part and a supporting member, the resistance heater part having a positive resistance-temperature characteristic in a temperature range above a predetermined level and exhibiting a nonlinear change in resistance when a temperature thereof exceeds the predetermined level, and the supporting member being insulative and supporting the resistance heater part such that the resistance heater part applies heat to the recording sheet passing through the fixing nip;
• a current detector detecting a current supplied to the resistance heater part;
• and
• an abnormality determiner determining whether the resistance heater part has an abnormality, based on an initial current detected by the current detector at a predetermined time after a beginning of power supply to the resistance heater part and before the temperature of the resistance heater part reaches the predetermined level;
• wherein the fixing device is provided with a power save mode in which power supply to the resistance heater part is reduced, and
• the abnormality determiner determines whether the resistance heater part has an abnormality when receiving an initial power supply instruction issued after the fixing device has entered the power save mode, and does not perform the determination when receiving a power supply instruction that is not the initial power supply instruction issued after the fixing device has entered the power save mode.