Engine

An engine (1) includes: a piston (9); a carburetor (25) having a diaphragm fuel pump (109), the diaphragm fuel pump (109) including a pump chamber (1118) configured to suck and discharge fuel and a diaphragm chamber (110) to which a pressure to drive the pump chamber (1118) is applied; and a communicating passage (104) configured to connect between the diaphragm chamber (110) and a negative pressure part in which a negative pressure is created due to movement of the piston (9) . A flowback prevention part (115) is formed in the communicating passage (104) to allow fluid to move only in on direction from the diaphragm chamber (110) to the negative pressure part.