A scintillator array comprising: a first scintillator element; a second scintillator element; and a reflector provided between the first and second scintillator elements and having a width of 80 μm or less therebetween, wherein: each scintillator element includes a polycrystal containing a rare earth oxysulfide phosphor, the polycrystal having a radiation incident surface of 1 mm or less × 1 mm or less in area; an average crystal grain diameter of the polycrystal is not less than 5 μm nor more than 30 μm, the average crystal grain diameter being defined by an average intercept length of crystal grains in an observation image of the polycrystal with a scanning electron microscope; and the rare earth oxysulfide phosphor is expressed by the formula A 2 O 2 S:Pr or by the formula (Gd 1-x A' x) 2 O 2 S:Pr, in which A represents at least one element selected from the group consisting of Y, Gd, La and Lu, A' represents at least one element selected from the group consisting of Y, La and Lu, and x represents a number satisfying 0 ≤ x ≤ 0.1; characterized in that the rare earth oxysulfide phosphor contains at least one element selected from the group consisting of Ce, Zr and P as a coactivator in addition to Pr as the main activator; a total amount of the at least one coactivator is not less than 0.00001 mol% nor more than 0.1 mol% relative to an amount of the phosphor host of the rare earth oxysulfide phosphor; and a maximum length or a maximum diameter of defects on the polycrystal is 40 μm or less. a first scintillator element; a second scintillator element; and a reflector provided between the first and second scintillator elements and having a width of 80 μm or less therebetween, wherein: each scintillator element includes a polycrystal containing a rare earth oxysulfide phosphor, the polycrystal having a radiation incident surface of 1 mm or less × 1 mm or less in area; an average crystal grain diameter of the polycrystal is not less than 5 μm nor more than 30 μm, the average crystal grain diameter being defined by an average intercept length of crystal grains in an observation image of the polycrystal with a scanning electron microscope; and the rare earth oxysulfide phosphor is expressed by the formula A 2 O 2 S:Pr or by the formula (Gd 1-x A' x) 2 O 2 S:Pr, in which A represents at least one element selected from the group consisting of Y, Gd, La and Lu, A' represents at least one element selected from the group consisting of Y, La and Lu, and x represents a number satisfying 0 ≤ x ≤ 0.1; characterized in that the rare earth oxysulfide phosphor contains at least one element selected from the group consisting of Ce, Zr and P as a coactivator in addition to Pr as the main activator; a total amount of the at least one coactivator is not less than 0.00001 mol% nor more than 0.1 mol% relative to an amount of the phosphor host of the rare earth oxysulfide phosphor; and a maximum length or a maximum diameter of defects on the polycrystal is 40 μm or less. each scintillator element includes a polycrystal containing a rare earth oxysulfide phosphor, the polycrystal having a radiation incident surface of 1 mm or less × 1 mm or less in area; an average crystal grain diameter of the polycrystal is not less than 5 μm nor more than 30 μm, the average crystal grain diameter being defined by an average intercept length of crystal grains in an observation image of the polycrystal with a scanning electron microscope; and the rare earth oxysulfide phosphor is expressed by the formula A 2 O 2 S:Pr or by the formula (Gd 1-x A' x) 2 O 2 S:Pr, in which A represents at least one element selected from the group consisting of Y, Gd, La and Lu, A' represents at least one element selected from the group consisting of Y, La and Lu, and x represents a number satisfying 0 ≤ x ≤ 0.1; characterized in that the rare earth oxysulfide phosphor contains at least one element selected from the group consisting of Ce, Zr and P as a coactivator in addition to Pr as the main activator; a total amount of the at least one coactivator is not less than 0.00001 mol% nor more than 0.1 mol% relative to an amount of the phosphor host of the rare earth oxysulfide phosphor; and a maximum length or a maximum diameter of defects on the polycrystal is 40 μm or less.