A gas engine air-conditioning device includes an outdoor unit having a gas engine, a first cooling water circulation flow passage and a second cooling water circulation flow passage, a first radiator, a second radiator, a water passage switch valve, a gas engine direct current power generator, a motor, a compressor, a condenser, and first fan, and a second fan, and is configured such that during heating, cooling water is circulated through the first cooling water circulation flow passage by a water passage switch valve, high-temperature passing air is sent from the first radiator, which reaches a high temperature, to the condenser by the first fan, and a refrigerant compressed by the compressor is circulated to an indoor unit, and during cooling, the cooling water is caused to flow through the second cooling water circulation flow passage by the water passage switch valve.