PURPOSE: To prevent the deterioration of startability and acceleration feature of two-cycle internal-combustion engine using low-quality fuel by providing a heating means near an ignition plug in a combustion chamber.

CONSTITUTION: A combustion chamber 38 is formed on the cylinder 12 side of a cylinder head 36, and an ignition plug 40 is arranged in the combustion chamber 38. A glow plug 42 for heating the mixed air is arranged near the ignition plug 40 upstream the flow of the mixed air moving toward the ignition plug 40, thereby the low quality fuel is heated and formed into an excellent atomized state before it is ignited by the ignition plug 40. Therefore, the startability and acceleration feature can be improved.