To explore new radiophotoluminescence (RPL) materials, Eu-doped CaSiO3 was synthesized by a solid-state reaction method, and its RPL behavior was evaluated from the viewpoint of radiation detection applications. X-ray diffraction (XRD) analysis confirmed that all samples were single-phase CaSiO3. After X-ray irradiation, a broad emission band attributed to the formation of Eu2+ centers was observed, indicating that the Eu-doped CaSiO3 host material exhibits distinct RPL behavior. The RPL sensitivity to radiation was highest at an Eu concentration of 0.1 mol%, with a linear dose response range from 0.18 Gy to at least 10 Gy. The Eu2+ centers generated by irradiation were highly stable, showing only a 7% signal decrease after 20 min. Upon heat treatment, the photoluminescence (PL) spectra exhibited significant changes, accompanied by the emergence of a new broad emission band. Analysis revealed a decrease in the Eu2+ emission and a corresponding increase in the Eu3+ emission, suggesting a possible valence change from Eu2+ to Eu3+. Furthermore, this broad emission becomes prominent at around 300 ℃ and above 400 ℃ and is also observed in undoped samples. The emission is considered to originate from defect centers formed within the host material during heat treatment.