To provide an engine capable of improving mountability to a working vehicle.

This engine 1 includes a thermostat case 27 for storing a thermostat 26 and arranged on one side surface (a front face) in the crankshaft 3 direction of a cylinder head 5. A cooling water pump 25 has a pump case 30 for rotatably journaling a cooling water pump shaft 29. The pump case 30 is arranged in layers with the thermostat case 27 (an installation part 272) in the crankshaft 3 direction (the longitudinal direction).