The inorganic scintillator of the invention is an inorganic scintillator capable of producing scintillation by radiation, which is a crystal comprising a metal oxide containing Lu, Gd, Ce and Si and belonging to space group C2/c monoclinic crystals, and which simultaneously satisfies the conditions specified by the following inequalities (1) and (2). {A.sub.Lu/(A.sub.Lu+A.sub.Gd)}<0.50 (1) {A.sub.Ce/(A.sub.Lu+A.sub.Gd)}.gtoreq.0.002 (2) wherein A.sub.Lu represents the number of Lu atoms in the crystal, A.sub.Gd represents the number of Gd atoms in the crystal, and A.sub.Ce represents the number of Ce atoms in the crystal.