A magnetic storage apparatus capable of performing storage data to a ferromagnetic tunnel junction device surely and with a low electric consumption. In the present invention, a magnetic storage apparatus using a ferromagnetic tunnel junction device configured so as to perform writing of storage data into the ferromagnetic tunnel junction device by applying writing magnetic force on the ferromagnetic tunnel junction device and to perform reading of storage data written in the ferromagnetic tunnel junction device by detecting a resistance value of the ferromagnetic tunnel junction device is provided, wherein it is configured to be able to change the magnitude of the writing magnetic force.