An electro-magnetically operable valve serving especially as fuel injection valve for a fuel injection device of internal combustion engines. The valve is composed of a valve housing, in which a magnetic coil is disposed around a core. The core has a concavely formed stop face against which, during excitation of the magnetic coil, a ball rests. The ball serves as an armature and movable valve part and cooperates with a fixed valve seat. The radius (r.sub.1) of the concavely formed stop face of the core is larger by about 0.1 to 1 mm than the radius (r.sub.2) of the ball. This causes a sufficient hydraulic cushion between the end face of the core and the ball when the ball is attracted toward the core upon magnetic energization of the latter and thus prevents a bouncing movement of the ball or its sticking to the core, when the ball is biased toward the valve seat upon de-energization of the core.