To enhance estimation accuracy of the temperature of a rotor magnet by correcting the counter electromotive voltage characteristics appropriately, in a controller of a dynamo electric machine.

A controller 16 of a dynamo electric machine 12 for estimating the temperature of the rotor magnet 24 of the dynamo electric machine 12 by using the counter electromotive voltage characteristics defining the relationship of counter electromotive voltage and temperature, includes a counter electromotive voltage calculation unit 62 for calculating the counter electromotive voltage of the dynamo electric machine 12 during operation, a coolant temperature acquisition unit 64 for acquiring the temperature of coolant for cooling the dynamo electric machine 12, a characteristics correction unit 66 for correcting the counter electromotive voltage characteristics based on the counter electromotive voltage thus calculated and the temperature of coolant thus acquired, and a temperature estimation unit 68 for estimating temperature of the rotor magnet 24 by using the counter electromotive voltage characteristics thus corrected.