POWER CONVERSION DEVICE

A power conversion device (1) configured to perform power conversion between a DC circuit (14) and an AC circuit (12) includes power conversion circuitry (2) including a plurality of submodules (7) connected in series to each other. The power conversion device (1) further includes: a signal reception unit (110) configured to receive a signal representing a voltage of a capacitor (24) in each of the submodules (7); a time calculation unit (130) configured to calculate at least one of a charging time of the capacitor (24) and a discharging time of the capacitor (24) based on the signal; and a determination unit (160) configured to determine whether the capacitor (24) has degraded or not based on at least one of a first result of comparison of the charging time with a reference charging time serving as a reference for determining degradation of the capacitor (24), and a second result of comparison of the discharging time with a reference discharging time serving as a reference for determining degradation of the capacitor (24).