A sound collecting unit (10) mounted on a vehicle is configured to collect sounds, a frequency resolution unit (21c) is configured to perform frequency analysis on the collected sound information, and when an object around the vehicle is detected based on a frequency characteristic of the sound information, a traveling sound detecting unit (21d) is configured to perform object detection such that object detection using a predetermined frequency band when a sound pressure of the predetermined frequency band is high in a frequency characteristic of a sound reproduced from a reproduction unit (11) mounted on the vehicle is more suppressed than object detection using a predetermined frequency band when a sound pressure of the predetermined frequency band is low in the frequency characteristic of the sound reproduced from a reproduction unit (11).