In an electromagnetically moving device (100), a magnetic-flux variation measuring unit (3) is placed at a position which is outside a closed magnetic path established when a movable core (6) and a stationary core (5) are being attached to each other due to permanent magnets (7), and at which a leakage magnetic-flux variation due to movement of the movable core (6) can be measured, so that a behavior of a movable part in a switch, etc. is estimated such that an inflection point time is calculated from the measurement of time-series data of the magnetic-flux variation.