PURPOSE: To utilize even the outward size of NaI crystal as a gamma-ray incidence detectable range by coupling a light transmitting material which passes converted visual light with the flank of a scintillator consisting principally of the NaI crystal.

CONSTITUTION: The scintillator part of the detector of the scintillator camera is composed of the scintillator 1 of NaI crystal, an optical window 2, a gamma- ray incidence window 3, and a support flange 4. Then the light transmitting material 5 which is coupled optically with the NaI crystal so as to pass the converted visible light of gamma rays without absorption, refraction, and reflection is provided at the periphery of the scintillator 1. Consequently, the visible light which is converted from the gamma rays at the periphery of the scintillator 1 is guided to a photoelectron multiplier tube without any trouble and the gamma-ray incidence position is detected even at the peripheral part of the NaI crystal.