A temperature estimation apparatus for a rotating electric machine includes a coolant dissipator, a heat dissipation amount calculator, a coolant temperature calculator, and a temperature calculator. The coolant dissipator is to cool down a coolant by heat exchange with a cooling air outside a rotating electric machine. The heat dissipation amount calculator is to calculate heat dissipation amount of the coolant in the coolant dissipator based on a physical quantity correlating with air speed of the cooling air and a physical quantity correlating with flow rate of the coolant. The coolant temperature calculator is to calculate, based on the heat dissipation amount, temperature of the coolant that has passed through the coolant dissipator. The temperature calculator is to calculate, based on the temperature of the coolant, temperature of the rotating electric machine which the coolant cool down.