The purpose of this study is to clarify the possibility of continuous measurement on cell proliferation and calcification using a scintillator-incorporated culture plate (Cytostar-T). Mouse osteoblast-like cells (MC3T3-E1) were cultured using culture plates (Cytostar-T) with culture media including two nuclides (³H-thymidine and ⁴⁵CaCl₂), followed by continuous measurements of ³H and ⁴⁵Ca were performed in the same well for 21 days using a micro-plate scintillation counter. The results showed it was possible to measure both cell number and the amount of calcification simultaneously and continuously. These results indicate that measurement using a scintillator-incorporated culture plate is promising method with improving the efficiency of the cells, the reagents and the materials used in vitro tests.