A four-cycle engine typically including a crankshaft provided with a first gear, a camshaft provided with a second gear, an endless rotation transmission that is installed around the first and second gears and is configured to transmit rotation of the crankshaft to the camshaft, a crank phase detecting device configured to detect a rotational phase of the crankshaft that is obtained by dividing a phase corresponding to one rotation of the crankshaft by a number that is equal to or more than a half of teeth of the second gear of the camshaft, and a cam phase detecting device configured to detect at least one rotational phase of the camshaft.