NOVELTY - The solenoid (10A) has an electromagnetic coil (13) pulling a plunger (11) i.e. movable core, toward a fixed core (12) while the coil is energized. A casing (14) houses the plunger, the core, and the coil. An end portion (11a1) of a plunger projection (11a) and an end portion (12c1) of a core projection (12c) include an acute angle in a cross section along an axial direction (G), where distance between the end portions of the plunger projection and the core projection is smaller than distance between the core and the plunger while the coil is not energized.    USE - Solenoid for use in a solenoid valve (claimed) of hydrogen tanks of fuel-cell vehicles.    ADVANTAGE - The end portion of the core projection and the end portion of the plunger projection have an acute angle in cross section along the axial direction, and the end portion of the core projection and the end portion of the plunger projection are closest to each other when the electromagnetic coil is not energized, so that the magnetic flux effectively concentrates at a thrust-generating portion i.e. gap portion, thus increasing the thrust generated by the solenoid in the initial stage of operation even while the stroke is large without adding another component to the basic structure of the solenoid. The solenoid does not increase magnetomotive force of the electromagnetic coil to generate sufficient thrust in the initial stage of operation, so that electric power for energizing the coil and size of the coil can be prevented from being increased, and a need of an expensive material with good magnetic characteristics is prevented. The solenoid has simple structure.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a solenoid valve.    DESCRIPTION OF DRAWING(S) - The drawing shows a longitudinal sectional view of a solenoid.    Axial direction (G)    Solenoid (10A)    Plunger (11)    Plunger projection (11a)    End portion of plunger projection (11a1)    Fixed core (12)    Core projection (12c)    End portion of core projection (12c1)    Electromagnetic coil (13)    Casing (14)