To provide an engine for working machine and an working machine using such an engine which can improve the versatility of the engine for working machine and improve the safety by preventing cooling air heated by the engine from being discharged towards a worker using the working machine.

The air which flows through a front side cooling air flow passage 29a and an upper side cooling air flow passage 29b provided in the front side and the upper side inside a casing 29 and the air which flows through an auxiliary air flow passage 29c provided in the back side inside the casing 29 join together near an opening 29e. By this, the direction of the air flowing from the front side towards the back side through the front side cooling air flow passage 29a and the upper side cooling air flow passage 29b can be changed by the air flowing through the auxiliary air flow passage 29c.