A solenoid apparatus includes a fixed core, a coil, and a movable core. The coil generates magnetic attractive force when the coil is supplied with electricity. The movable core is attracted to the fixed core by the magnetic attractive force generated between the fixed core and the movable core when the coil is supplied with electricity. The fixed core has a fixed axial end on a side of the movable core. The movable core has a movable axial end on a side of the fixed core. At least one of the fixed axial end and the movable axial end has at least one recession. The at least one of the fixed axial end and the movable axial end, which has the at least one recession, has an outer circumferential periphery and an inner circumferential periphery. The outer circumferential periphery radially communicates with the inner circumferential periphery through the at least one recession.