A barium titanate-based semiconductor ceramic composition and a PTC element that have a high Curie temperature and a low electrical resistivity at room temperature and that exhibit a desired rate of change in resistance are provided. The barium titanate-based semiconductor ceramic composition is a ceramic composition having a perovskite structure containing at least barium and titanium, wherein some of the barium is replaced with an alkali metal element, bismuth, and a rare earth element, and when the content of the titanium is assumed to be 100 parts by mole, a ratio of the content of the alkali metal element to the content of the bismuth plus the content of the rare earth element represented by parts by mole, is 1.00 or more and 1.06 or less. A PTC thermistor includes a ceramic body composed of the barium titanate-based semiconductor ceramic composition having the above feature and electrodes disposed on both side faces of the ceramic body.