A surveillance apparatus (2000) includes a first calculation unit (2020), an extraction unit (2040), and a notification unit (2060). The first calculation unit (2020) calculates a risk index value in a first region (40) on a current route (20). The risk index value of the first region (40) indicates a degree of concern that a risk (such as crowd confusion) caused by congestion of people occurs in the first region (40). For calculation of the risk index value in the first region (40), a captured image generated by a camera (50) is used. The extraction unit (2040) extracts a bypass route (30) when the risk index value of the first region (40) is equal to or greater than a predetermined threshold value. The notification unit (2060) notifies a user that a route through which a person is caused to pass is to be switched to the extracted bypass route (30).