For applications in a facility where a power conversion apparatus is frequently started and stopped, a power conversion apparatus and a power cycle longevity estimation method are provided which improve an ease of use of the facility. The power conversion apparatus comprises power conversion circuits to supply ac power of variable voltage and variable frequency, a detection circuit to detect a temperature of the power semiconductor in the power conversion circuits, and a computation device to calculate a power cycle longevity of the power semiconductor based on a maximum temperature rise detected by the detection circuit.