To provide an engine with a governor capable of simplifying a constitution, capable of reducing the size and weight, and capable of securing smooth valve system operation.

This engine 1 with the governor has the governor 20 rotatably installed in a cylinder block 2 via a support shaft 21 and adjusting an engine speed on the basis of rotation of a governor case 22 synchronously rotating with a crankshaft 6. The engine has a timing belt 15 extended between a driving side timing belt pulley 11 arranged on the crankshaft 6 and a driven side timing belt pulley 13 arranged on a camshaft 8. A pulley 23 is formed on the outer periphery of the governor case 22, and rotatingly drives the governor case 22 by being brought into pressure contact with an outer peripheral surface 18 of the timing belt 15 between both timing belt pulleys 11 and 13, and applies tension to the timing belt 15.