A photodetector for detecting an energy line in a first wavelength region and an energy line in a second wavelength region on a longer wavelength side than the first wavelength region, the photodetector comprising: a first semiconductor layer having a predetermined resistivity; an insulating layer laid on a main face on first side of the first semiconductor layer; a second semiconductor layer laid on a main face on the first side of the insulating layer and having a resistivity higher than the predetermined resistivity; a wiring film disposed on a main face on the first side of the second semiconductor layer while interposing an insulating film therebetween and electrically connected to an electric passage part included in the first semiconductor layer; a first photosemiconductor element disposed on a main face on second side of the first semiconductor layer so as to cover a recess formed on the main face on the second side of the first semiconductor layer and secure hermeticity within the recess and electrically connected to the electric passage part; and a second photosemiconductor element placed within the recess and electrically connected to the first photosemiconductor element; wherein the first photosemiconductor element comprises: a first semiconductor substrate and a first photoelectric conversion unit disposed on a part on the first side of the first semiconductor substrate, for generating an electric charge when the energy line in the first wavelength region is incident on the first semiconductor substrate from the second side; and wherein the second photosemiconductor element comprises: a second semiconductor substrate and a second photoelectric conversion unit disposed on a part on the second side of the second semiconductor substrate so as to oppose the first photoelectric conversion unit, for generating an electric charge when the energy line in the second wavelength region is incident on the second semiconductor substrate from the second side. a first semiconductor layer having a predetermined resistivity; an insulating layer laid on a main face on first side of the first semiconductor layer; a second semiconductor layer laid on a main face on the first side of the insulating layer and having a resistivity higher than the predetermined resistivity; a wiring film disposed on a main face on the first side of the second semiconductor layer while interposing an insulating film therebetween and electrically connected to an electric passage part included in the first semiconductor layer; a first photosemiconductor element disposed on a main face on second side of the first semiconductor layer so as to cover a recess formed on the main face on the second side of the first semiconductor layer and secure hermeticity within the recess and electrically connected to the electric passage part; and a second photosemiconductor element placed within the recess and electrically connected to the first photosemiconductor element; wherein the first photosemiconductor element comprises: a first semiconductor substrate and a first photoelectric conversion unit disposed on a part on the first side of the first semiconductor substrate, for generating an electric charge when the energy line in the first wavelength region is incident on the first semiconductor substrate from the second side; and wherein the second photosemiconductor element comprises: a second semiconductor substrate and a second photoelectric conversion unit disposed on a part on the second side of the second semiconductor substrate so as to oppose the first photoelectric conversion unit, for generating an electric charge when the energy line in the second wavelength region is incident on the second semiconductor substrate from the second side. a first semiconductor substrate and a first photoelectric conversion unit disposed on a part on the first side of the first semiconductor substrate, for generating an electric charge when the energy line in the first wavelength region is incident on the first semiconductor substrate from the second side; and wherein the second photosemiconductor element comprises: a second semiconductor substrate and a second photoelectric conversion unit disposed on a part on the second side of the second semiconductor substrate so as to oppose the first photoelectric conversion unit, for generating an electric charge when the energy line in the second wavelength region is incident on the second semiconductor substrate from the second side. a second semiconductor substrate and a second photoelectric conversion unit disposed on a part on the second side of the second semiconductor substrate so as to oppose the first photoelectric conversion unit, for generating an electric charge when the energy line in the second wavelength region is incident on the second semiconductor substrate from the second side.