Abstract: A torch ignition type internal combustion engine with no intake valve in the auxiliary combustion chamber, the engine comprising: a cylinder; a cylinder head; a reciprocating piston received snugly in the cylinder; a main combustion chamber defined between said cylinder head and an end face of the reciprocating piston and having intake and exhaust valves to control intake and exhaust ports in the cylinder head; an auxiliary combustion chamber provided in the head of the cylinder; a passage interconnecting said main and auxiliary combustion chambers; and an ignition plug having sparking electrodes located in said passage; the auxiliary combustion chamber having a volume of a ratio within the range of 0.0106:1 to 0.0137:1 with respect to the volume of displacement of the piston, the passage having a cross-sectional area of a ratio within the range of 0.009:1 to 0.023:1 with respect to the cross-sectional area of the end face of the piston and the engine having a compression ratio within the range of 8.0 to 9.5.