A control device (34) for driving/controlling an engine (10) on the basis of a signal from a temperature state detector (30), a rotation detector (31), and a rotational speed setting device (32) are provided. The control device (34) includes a start temperature determining processing unit configured to determine whether or not a temperature (T) at start of the engine (10) has lowered to a predetermined temperature (Tw1) and a start control processing unit configured to perform start control of the engine (10) in accordance with a set value of a target rotational speed (Nset) by the rotational speed setting device (32) in case the start temperature determining processing unit determines that the temperature (T) is equal to or less than the predetermined temperature (Tw1). This start control processing unit suppresses occurrence of cavitation by stopping the start of the engine (10) within a range in which the temperature (T) is equal to or lower than the predetermined temperature (Tw1) and the target rotational speed (Nset) of the engine (10) is higher than a predetermined threshold value (Nca).