PURPOSE: To improve the driving operation performance and safety by releasing the active state of a wiper driving part when the next detection signal is not output within a certain time after the time point when a raindrop sensor stops outputting detection signal and by alarming said release.

CONSTITUTION: When a manual switch 6 is pressed, a microcomputer 7a sets a wiper driving part 7 into active state and operates an alarm means 8 and turns-ON the indication lamp L of said means. Further, the microcomputer 7a sets a raindrop sensor 3 into active state. When a detection signal is output from the raindrop sensor 3, the microcomputer 7a operates a wiper driving part 4 to operate a wiper. When the next signal is not output within the time set on a timer which is memorized into the ROM of the microcomputer 7a, the microcomputer 7a releases the active state of the wiper driving part 4. In other words, automatic wiper mode is released. In this case, the microcomputer 7 puts out the indication lamp L after putting ON and OFF the lamp several times and sets the raindrop sensor 3 into inactive state.