A gas fireplace includes a furnace, a burner, and an air guiding device, wherein the air guiding device divides an inside of the furnace into a first chamber and a second chamber; the burner is provided in the second chamber; an air outlet of the furnace communicates with the first chamber; the air guiding device has a passageway communicating the first chamber and the second chamber, wherein a width of the passageway gradually narrows from the second chamber to the first chamber. Whereby, the hot air generated while the burner is burning gas enters the first chamber from the second chamber through the air guiding device, and then can be smoothly exhausted to outside.