A charged particle beam apparatus that includes a magnetic lens having an electromagnetic coil composed of a pair of coils includes: a setting unit that sets a maximum current value that defines a maximum magnetomotive force of the magnetic lens based on an operation of a user; and a current control unit that controls a current to be supplied to each of the pair of coils within a current range corresponding to a set maximum current value so that thermal power consumed by the electromagnetic coil is maintained constant at thermal power corresponding to the set maximum current value.