In the present invention, to conduct multiple molecular imaging in a PET device, both a first probe and a second probe, each of which has a nuclide that emits unique gamma rays as a result of gamma decay after beta decay, are administered to a subject to be imaged, and then the image capturing is performed by a multiple probe PET device (100). The multiple probe PET device (100) is provided with a group of PET gamma ray detectors (10) and an energy-resolving gamma ray detector (20), and, when an imaging processor (30) executes image reconstruction based on a pair-annihilation detection signal from the group of PET gamma ray detectors (10), images are reconstructed differently according to the energy values of the unique gamma rays. Imaging can also be carried out using a nuclide that does not emit any unique gamma ray and a nuclide that emits a unique gamma ray.