An engine which is a single cylinder engine comprising: a cylinder section including a combustion chamber; a valve (24 - 27) supported by the cylinder section, the valve (24 - 27) being configured to open and close an exhaust port or an intake port in the combustion chamber; a cam shaft including an intake cam (144, 145) and an exhaust cam, the cam shaft being supported by the cylinder section; a rocker shaft supported by the cylinder section, the rocker shaft being parallel to the cam shaft; a first rocker arm supported by the rocker shaft, the first rocker arm including one end section configured to be able to make contact with the cam shaft and the other end section configured to be able to make contact with the valve (24 - 27), the first rocker arm being configured to be operated in a direction in which the valve (24 - 27) is pressed down; a second rocker arm supported by the rocker shaft, the second rocker arm including one end section configured to be able to make contact with the cam shaft, the second rocker arm being arranged to line up with the first rocker arm in an axial direction of the cam shaft; a switching pin member configured to be moved in the axial direction of the cam shaft, the switching pin member being configured to be moved between a first position at which the first rocker arm and the second rocker arm are linked and a second position at which the first rocker arm and the second rocker arm are not linked, the switching pin member being configured to swing together with the first rocker arm and the second rocker arm at the first position; and an actuator configured to switch the position of the switching pin member between the first position and the second position by pressurizing the switching pin member in the axial direction of the cam shaft, the actuator includes a rod for pressurizing the switching pin member and a body section for driving the rod characterized in that the switching pin member is positioned on an end section side of the valve (24 - 27) with regard to the rocker shaft when viewed from the axial direction of the cam shaft. a cylinder section including a combustion chamber; a valve (24 - 27) supported by the cylinder section, the valve (24 - 27) being configured to open and close an exhaust port or an intake port in the combustion chamber; a cam shaft including an intake cam (144, 145) and an exhaust cam, the cam shaft being supported by the cylinder section; a rocker shaft supported by the cylinder section, the rocker shaft being parallel to the cam shaft; a first rocker arm supported by the rocker shaft, the first rocker arm including one end section configured to be able to make contact with the cam shaft and the other end section configured to be able to make contact with the valve (24 - 27), the first rocker arm being configured to be operated in a direction in which the valve (24 - 27) is pressed down; a second rocker arm supported by the rocker shaft, the second rocker arm including one end section configured to be able to make contact with the cam shaft, the second rocker arm being arranged to line up with the first rocker arm in an axial direction of the cam shaft; a switching pin member configured to be moved in the axial direction of the cam shaft, the switching pin member being configured to be moved between a first position at which the first rocker arm and the second rocker arm are linked and a second position at which the first rocker arm and the second rocker arm are not linked, the switching pin member being configured to swing together with the first rocker arm and the second rocker arm at the first position; and an actuator configured to switch the position of the switching pin member between the first position and the second position by pressurizing the switching pin member in the axial direction of the cam shaft, the actuator includes a rod for pressurizing the switching pin member and a body section for driving the rod the switching pin member is positioned on an end section side of the valve (24 - 27) with regard to the rocker shaft when viewed from the axial direction of the cam shaft.