An arctangent calculation apparatus includes a phase angle memory unit in which a phase angle is stored in advance, the phase angle corresponding to a two-dimensional vector value corresponding to in a range of 0° to substantially 22.5°; a vector rotation unit that performs a vector rotation operation on a two-dimensional vector value corresponding to in a range of 0° to 360° and converts the two-dimensional vector value corresponding to in a range of 0° to 360° into a two-dimensional vector value corresponding to in a range of 0° to substantially 2.5°; an arctangent calculation unit that outputs, from the phase angle memory unit, a phase angle that corresponds to the two-dimensional vector value corresponding to in a range of 0° to substantially 22.5°; and a phase angle conversion unit that converts the phase angle into a phase angle in a range of 0° to 360°.