Disclosed is a two-cycle internal combustion engine including a protruding edge portion formed in a section of a lower side surface of an intake port which is adjacent to a pre-compression chamber of a cylinder. This protruding edge portion serves to deflect air-fuel mixture introduced into the pre-compression chamber through the intake port so as to direct it to a bearing portion provided between a piston and a connecting rod. Further, a cut-in groove is formed in the protruding edge section and is adapted to allow any liquid remaining in the intake port to flow into the pre-comparison chamber.