Provided is a scintillator used for radiation detection in an X-ray CT scanner or the like, the scintillator having a unidirectional phase separation structure having an optical waveguide function, which eliminates the need of formation of banks for preventing crosstalk. The scintillator has a waveguide function instead of the banks or the like. The scintillator includes: a first crystal phase including multiple columnar crystals having unidirectionality; and a second crystal phase for covering a side of the first crystal phase. The first crystal phase includes a perovskite type oxide material including at least one element selected from the group consisting of Lu and Gd, and a rare earth element as an emission center. The first crystal phase emits light by radiation excitation.
