A barium titanate based PTC thermistor ceramic composition without using Pb. Its Curie temperature is shifted to a temperature higher than 120° C. The PTC thermistor can readily turn semiconductive even if it is sintered in air. The resistivity at 25° C. is low and the variation rate of the resistivity at 25° C. with time is little. The PTC thermistor ceramic composition includes a sintered body having a barium titanate based compound represented by formula (1) as the main component, (Ba1-x-y-wBixAyREw)α(Ti1-zTMz)O3 (1), wherein, 1.02y≦x≦1.5y (2), 0.007≦y≦0.125 (3), 0≦(w+z)≦0.01 (4), 0.97≦α≦1.06 (5), and the sintered body contains Ca in a ratio of 0.01 mol or more and less than 0.05 mol relative to 1 mol of Ti site in terms of element.