Electrical resistance of single-crystalline CeAs, CeSb, and CeBi has been measured under hydrostatic pressure. In CeAs and CeSb, pressure enhances the change of overall features in the resistance-temperature R(T) curves. Resistance anomalies associated with magnetic phase transitions are observed and are found to be sensitive to pressure. It is noted that the R(T) curve of CeAs at approximately 3 GPa is similar to that of CeSb at ambient pressure.