According to one embodiment, a magnetic resonance imaging apparatus includes a mode switching part and an imaging system. The mode switching part is configured to put a circuit system consuming a power into a shutdown state when a first trigger has been detected and put the circuit system being the shutdown state into a startup state when a second trigger has been detected. The first trigger shows that an imaging does not start for a certain period. The second trigger shows that the imaging starts. The imaging system is configured to perform the imaging by using the circuit system being the startup state.