A gas turbine engine includes: a main passage through which compressed air extracted from a compressor is guided to a bearing; and an oil supply device that includes an oil tank storing oil and supplies the oil to the main passage through which the compressed air flows to generate oil mist. The oil supply device includes: a pressure reducer disposed at the main passage; a bypass passage that bypasses the pressure reducer and connects an upstream passage and a downstream passage; a holding chamber disposed at the bypass passage and having a predetermined volume; a switching mechanism that permits or blocks communication between the holding chamber and the oil tank, communication between the holding chamber and the upstream passage, and communication between the holding chamber and the downstream passage; and a controller that controls the switching mechanism.