A magneto-caloric effect type heat pump apparatus provides a thermo-magnetic cycle apparatus. A magnetic field modulating device has a rotary permanent magnet. By rotating the permanent magnet, magnetic field applied to a magneto-caloric element is modulated alternatively in a magnetized state and a demagnetized state. A magnetized period, when the magnetic field is applied, is shorter than a demagnetized period, when the magnetic field is removed. Thereby, it is possible to reduce weight of the magnetic field modulating device having the permanent magnet. The magneto-caloric element has a heat exchange portion which varies heat exchanging efficiency depending on flow directions of a heat transport medium. The heat exchanging efficiency in the magnetized period is higher than the heat exchanging efficiency in the demagnetized period. Therefore, it is possible to provide sufficient heat exchanging quantity even in a short magnetized period.