An automobile antenna control device generating a reset pulse which starts the operation of a microcomputer. The pulse is generated when an automobile radio power source is switched from "off" to "on," or when the power source is switched from "on" to "off," so that a so-called runaway of the microcomputer can be prevented. The power source is connected to an input port of the microcomputer; the antenna is extended when the power source is "on," and is retracted when the power source is "off." The extending or retracting action of the antenna is stopped when the starter power source of the master key switch of the automobile is "on."