An inclination sensor includes: a case having a turning shaft section projected in a lateral direction on a front surface thereof; magnetism detecting means fixed on an upper side of the turning shaft section; a pair of magnets fixed in parallel to a rear surface of the case to be located on both sides of the magnetism detecting means; a pendulum axially supported by the turning shaft section to turn freely; and a pair of ferromagnetic bodies fixed on an inward surface of the pendulum. When the case inclines, one of the ferromagnetic bodies approaches the magnetism detecting means, and a magnetic circuit is closed by the pair of magnets and one of the ferromagnetic bodies. Magnetic fluxes of the magnets pass over front and rear surfaces of the magnetism detecting means.