An abnormality detection device comprising: a detector configured to detect a shake of a vehicle; a vehicle information acquisition unit configured to acquire information about a driving state of the vehicle; a vehicle peripheral information acquisition unit configured to acquire at least one of a video around the vehicle, illuminance information around the vehicle, and sound information around the vehicle; a threshold setting unit configured to set at least one threshold (TH1, TH2) for determining whether the detected shake of the vehicle is abnormal, and configured to change the at least one threshold (TH1, TH2) based on the information acquired by the vehicle peripheral information acquisition unit when the vehicle is determined to be being parked based on the information about the driving state of the vehicle acquired by the vehicle information acquisition unit; and an abnormality determination unit configured to determine an abnormality based on sensor output values of the shake of the vehicle detected by the detector and compared with the at least one threshold (TH1, TH2) set by the threshold setting unit, characterized in that the threshold setting unit is further configured to change the at least one threshold (TH1, TH2) such that the abnormality is more easily determinable to have occurred in situations where a vehicle break-in or a mischief is likely to occur based on the information acquired by the vehicle peripheral information acquisition unit, wherein the vehicle break-in or the mischief is likely to occur when the vehicle peripheral information is the illuminance information around the vehicle and the acquired illuminance information is equal to or lower than a predetermined value, the vehicle break-in or the mischief is likely to occur when the vehicle peripheral information is the sound information around the vehicle and a sound volume of the acquired sound is equal to or lower than a predetermined value or equal to or higher than another predetermined value that has been separately set from the predetermined value, and when the vehicle peripheral information is the video around the vehicle and motion information that is a processing result obtained by known motion detection processing on the acquired captured video is equal to or higher than a predetermined value. a detector configured to detect a shake of a vehicle; a vehicle information acquisition unit configured to acquire information about a driving state of the vehicle; a vehicle peripheral information acquisition unit configured to acquire at least one of a video around the vehicle, illuminance information around the vehicle, and sound information around the vehicle; a threshold setting unit configured to set at least one threshold (TH1, TH2) for determining whether the detected shake of the vehicle is abnormal, and configured to change the at least one threshold (TH1, TH2) based on the information acquired by the vehicle peripheral information acquisition unit when the vehicle is determined to be being parked based on the information about the driving state of the vehicle acquired by the vehicle information acquisition unit; and an abnormality determination unit configured to determine an abnormality based on sensor output values of the shake of the vehicle detected by the detector and compared with the at least one threshold (TH1, TH2) set by the threshold setting unit, characterized in that the threshold setting unit is further configured to change the at least one threshold (TH1, TH2) such that the abnormality is more easily determinable to have occurred in situations where a vehicle break-in or a mischief is likely to occur based on the information acquired by the vehicle peripheral information acquisition unit, wherein the vehicle break-in or the mischief is likely to occur when the vehicle peripheral information is the illuminance information around the vehicle and the acquired illuminance information is equal to or lower than a predetermined value, the vehicle break-in or the mischief is likely to occur when the vehicle peripheral information is the sound information around the vehicle and a sound volume of the acquired sound is equal to or lower than a predetermined value or equal to or higher than another predetermined value that has been separately set from the predetermined value, and when the vehicle peripheral information is the video around the vehicle and motion information that is a processing result obtained by known motion detection processing on the acquired captured video is equal to or higher than a predetermined value.