The number of annual death accidents while bathing has been estimated at approximately 14000 in Japan. The death accidents could be avoided by recognizing the bather's situation and treating them quickly, as well as preventive measures. In previous study, fall detection system using CCD camera, infrared sensor and ultrasonic sensors have been researched and developed, but those system is an invasion of privacy and high cost. This paper presents a system for high accuracy the detection of bather's fall using photodetecters at a low cost. In addtion, the action is detected using improved histograms of oriented gradients. The comparative experiments have shown that the rate of detecting hit of the front, and hit of back has increased by 14%, 9% respectively. Moreover, the experimental result of using the proposed system in the bathroom have shown that the efficiency of the photodetectors can hardly be reduced by shower, steams and outside light.