The purpose of this study is to prevent the stick, scuffing, scratch between piston and cylinder, is to contribute the piston design such as piston profile, clearance by calculating reaction force by over-lap of piston skirt, as measuring the temperature distributions of cylinder wall. The experiment has been peformed to obtain data during actual engine operation. Temperature gradient in peripheral and axial distributions of cylinder wall according to torque and speed of engine were measured by use of an 800cc class gasoline engine. The results obtained are summarized as follows ; 1) The temperature of cylinder wall at TDC was about $50{sim}75^{circ}C$ higher than temperature of cooling water. 2) The rear side temperature of top dead center was $141^{circ}C$(1/4 load) in axial distribution, whereas the rear side of midway position temperature was $98^{circ}C$. 3) The temperature of cylinder wall increased in according to rising temperature of cooling water. 4) The thrust side temperature of cylinder wall was about $15^{circ}C$ in all load test. 5) The rear side temperature of top dead center was $159^{circ}C$ (1/2 load) in peripheral distribution, it was about $39^{circ}C$ higher than thrust side temperature.