According to one embodiment, a radioactive ray detecting apparatus includes: a scintillator that produces visible light from a radioactive ray a light detecting portion including a light receiving element that generates an electrical signal on a basis of intensity of visible light a first board a first electrical connection unit that electrically connects the light detecting portion and a first surface of the first board to each other a second board disposed to face the first board a second electrical connection that electrically connects a first surface of the second board and a second surface of the first board being opposite from the first surface of the first board to each other and a data acquisition device that processes an electrical signal transmitted from the light detecting portion through the first electrical connection unit, the first board, the second electrical connection unit, and the second board.
