Image and sound information are acquired from a camera and a microphone and the information is stored into a second RAM for a first time period from detection of occurrence of an abnormal condition of a vehicle by a sensor. When occurrence of an abnormal condition of the vehicle has been detected by the sensor during the first time period from the detection of occurrence of an abnormal condition of the vehicle, image and sound information is acquired from the camera and the microphone and the information is stored into the second RAM for a second time period from the previous detection of occurrence of an abnormal condition of the vehicle, and the image and sound information stored into the second RAM for the second time period Tb are stored into a nonvolatile ROM.