To provide a two-cycle combustion engine, in which the blow-off of the air-fuel mixture used as the scavenging gas is avoided and the combustion efficiency of the air-fuel mixture can be increased, the two-cycle combustion engine includes first and second scavenge passages (11, 12) for supplying the air-fuel mixture (M) from a crank chamber (2a) into the combustion chamber (1a) of the combustion engine. Each of the first and second scavenge passages (11, 12) has a lower end portion thereof extended to assume the position where it confronts an outer end face of a bearing (81) for the crankshaft (8), so that the air-fuel mixture (M) within the crank chamber (2a) can be introduced into the first and second scavenge passages (11, 12) through the bearing (81) and be then supplied into the combustion chamber (1a) through the first and second scavenge passages (11, 12).