To provide an engine control device improving fuel economy of an engine by suppressing deterioration of durability of a cylinder bore caused by a sudden drop in temperature of the cylinder bore without increasing the weight of the cylinder bore.

The engine 1 includes a cooling water circulation system circulating cooling water through a cooling water passage 10 in the order of the cylinder block 3 and cylinder head 4 of the engine 1 when an electric water pump 11 is normally rotated. An electronic control device 20 operates the water pump 11 when a cooling water temperature THW exceeds a predetermined temperature T1 while stopping the water pump 11 when the cooling water temperature THW inside an engine body 2 is lower than the predetermined temperature T1. When the cooling water temperature THW inside of the engine body 2 exceeds the predetermined temperature T1, the water pump 11 is operated to rotate backward.