In a gas-liquid separation device in a vibrator engine according to the present invention, a crank chamber and a rocker chamber communicate with each other through an oil delivery passage, and a push rod chamber and the crank chamber communicate with each other through an oil chamber and an oil discharge port. Oil mist generated in the crank chamber flows into the rocker chamber through the oil delivery passage, as the oil discharge port begins to resist the flow. The mist flows into the push rod chamber after the mist is made into liquid for lubrication of parts to be lubricated. Thus, the oil is returned to the crank chamber from the oil delivery passage through the rocker chamber, the push rod chamber, and the oil chamber to form a circulating path. Accordingly, a larger quantity of oil than the required quantity is not stored in the rocker chamber, and a preferable amount of gas-liquid separation may be obtained even when effects caused by vigorous vertical vibration of a vibrator make the oil stored in the rocker chamber strongly shake.