A control apparatus for a gas sensor, wherein a microcomputer 44, which is connected to an oxygen sensor 30 including a detection element 12 and a heater 14, detects the cooling water temperature Tw of the engine. The control apparatus determines that condensation water within the exhaust pipe is being generated when the cooling water temperature Tw is equal to or lower than 0° C. When equal to or lower than 0° C., the microcomputer 44 supplies to the heater 14 electrical power for maintaining the temperature of the detection element 12 within the range of 100° C. to a splash-water-cracking generation temperature (e.g., about 300° C.) at or above which cracking can occur in a laminated-type oxygen sensor element 10 due to splash of condensation water. Electrical power is supplied to the heater 14 such that a pulse signal Sh is output from the microcomputer 44, and the heater 14 is pulse-driven by use of a heater electrification control circuit 34.