The force (N) is exerted on a core (12) and its surrounding sleeve (14) by the plunger (11). The core and sleeve are made of sintered magnetoelastic Ni-Fe alloy, and the same thrust is effective in both. A measuring coil (13) is located around the core and within the sleeve. Its inductance varies in response to change in permeability of the core and sleeve under stress. To concentrate the flux, a baseplate (15) under the core and sleeve is made of preferably ferromagnetic material.
