An object of the invention is to provide a technique that is safe and quantitative, and is capable of continuously acquiring a magnetic resonance image with a short repetition time.A magnetic resonance contrast agent comprising a polyethylene glycol containing 13C in a proportion higher than the natural abundance, or a compound labeled with the polyethylene glycol, is used to continuously acquire magnetic resonance signals by applying excitation pulses with a repetition time of 60 seconds or less.
