A target value of magnetic flux density and magnetic flux density actually obtained are made to coincide precisely with each other. An electromagnet control device comprises a current value determining unit for determining, based on a magnetic flux density instruction value, a value of current that is made to flow through a coil. The current value determining unit is constructed to execute a second process for determining, based on a second function, a value of the current, if the magnetic flux density is to be decreased from that in a first magnetization state, and a fourth process for expanding or reducing the second function by use of a first scaling ratio for transforming it to a fourth function, and determining, based on the fourth function obtained after above transformation, a value of the current, if the magnetic flux density is to be decreased from that in a third magnetization state.