A notification target detection device comprising: a vehicle information obtaining unit for obtaining vehicle information indicating a vehicle speed or a shifter position; a video obtaining unit for obtaining video in which a vehicle's interior is shot; a passenger presence-or-absence determining unit for determining that a passenger is present in the vehicle's interior when an image of the passenger except for a child or a pet that is a notification target, of which a person outside a vehicle is to be informed, is included in the video in the vehicle's interior obtained by the video obtaining unit and determining that the passenger is not present in the vehicle's interior when the image of the passenger that is not the notification target is not included in the video in the vehicle's interior obtained by the video obtaining unit; a voice obtaining unit for obtaining a voice in the vehicle's interior; a voice source determining unit (24, 24A to 24C) for determining whether a source of generation of the voice in the vehicle's interior is the notification target alone of which the person outside the vehicle is to be informed, based on the voice in the vehicle's interior obtained by the voice obtaining unit; and an object detecting unit for detecting an object related to the notification target in the vehicle's interior on a basis of the video obtained by the video obtaining unit, wherein the voice source determining unit (24, 24A to 24C) determines whether the source of generation of the voice in the vehicle's interior is the notification target alone when it has been determined that the vehicle speed is less than or equal to a threshold value or the shifter position is a park position on a basis of the vehicle information obtained by the vehicle information obtaining unit, and when the passenger presence-or-absence determining unit has determined that a passenger is not present in the vehicle's interior and the object detecting unit has detected an object related to the notification target in the vehicle's interior. a vehicle information obtaining unit for obtaining vehicle information indicating a vehicle speed or a shifter position; a video obtaining unit for obtaining video in which a vehicle's interior is shot; a passenger presence-or-absence determining unit for determining that a passenger is present in the vehicle's interior when an image of the passenger except for a child or a pet that is a notification target, of which a person outside a vehicle is to be informed, is included in the video in the vehicle's interior obtained by the video obtaining unit and determining that the passenger is not present in the vehicle's interior when the image of the passenger that is not the notification target is not included in the video in the vehicle's interior obtained by the video obtaining unit; a voice obtaining unit for obtaining a voice in the vehicle's interior; a voice source determining unit (24, 24A to 24C) for determining whether a source of generation of the voice in the vehicle's interior is the notification target alone of which the person outside the vehicle is to be informed, based on the voice in the vehicle's interior obtained by the voice obtaining unit; and an object detecting unit for detecting an object related to the notification target in the vehicle's interior on a basis of the video obtained by the video obtaining unit, wherein the voice source determining unit (24, 24A to 24C) determines whether the source of generation of the voice in the vehicle's interior is the notification target alone when it has been determined that the vehicle speed is less than or equal to a threshold value or the shifter position is a park position on a basis of the vehicle information obtained by the vehicle information obtaining unit, and when the passenger presence-or-absence determining unit has determined that a passenger is not present in the vehicle's interior and the object detecting unit has detected an object related to the notification target in the vehicle's interior.