Electromagnetic actuator

In the present invention, a through hole (33) through which a rod (17) is inserted is formed in an electromagnetic drive unit (MD), the rod (17) comprising an outer wall surface (42) that slides along the through hole (33). A clearance (CB) from the outer wall surface (42) of the rod (17) located in a maximum protrusion position to an inner wall surface (34) of the through hole (33) is smaller than a clearance (CA) from the outer wall surface (42) of the rod (17) located in a maximum retracted position to the inner wall surface (34). Through this, the clearance when retracted is relatively large, making it possible to reduce the friction forces between the rod (17) and a support tube portion (32). In addition, the clearance when protruded is relatively small, making it possible to reduce the amount a tip portion (44) of the rod (17) shakes in the radial direction. 在电磁驱动部(MD)上形成有供杆(17)插通的通孔(33)，杆(17)具有与通孔(33)滑动的外壁面(42)。从位于最大突出位置的杆(17)的外壁面(42)到通孔(33)的内壁面(34)的间隙(CB)比从位于最大拉入位置的杆(17)的外壁面(42)到内壁面(34)的间隙(CA)小。由此，通过拉