1. A machine learning apparatus that learns a condition associated with an arrangement position of a magnet on a core of a motor rotor, the machine learning apparatus comprising: a state observation unit that observes a state variable composed of data relating to arrangement positions of a plurality of magnets arranged on the core, data relating a magnitude of a cogging torque generated when the plurality of magnets are arranged at the respective arrangement positions, and data relating to a magnetic flux density of each of the magnets; and a learning unit that learns the condition associated with arrangement positions of the magnets on the core in accordance with a training data set constituted by the state variable.