1. A target detecting device, wherein the target detecting device is used mounted in a vehicle in order to avoid a collision between the vehicle and a target that is captured by a sensor mounted to the vehicle, the target detecting device comprising: a radar sensor being suitable for transmitting radar waves to a target present around a reference vehicle in which the target detecting device is mounted, and receiving a reflected waves from the target; an imaging sensor being suitable for capturing an image of an area around the reference vehicle; and an ECU, wherein the ECU comprises: a CPU; a target detecting first unit configured to enable the CPU to detect a target using information acquired by the radar sensor; a selecting unit configured to enable the CPU to select a target that satisfies a predetermined condition, among targets detected by the radar sensor; an output unit configured to enable the CPU to output information on the target selected by the selecting unit; a stopped vehicle detecting unit configured to enable the CPU to detect a stopped vehicle present around the reference vehicle; and a target detecting second unit configured to enable the CPU to detect a target from the image acquired by the imaging sensor by performing image recognition using predetermined patterns of a target, wherein, when the stopped vehicle detecting unit detects a stopped vehicle and the target detecting second unit detects a target present behind the stopped vehicle, the selecting unit makes the predetermined selection condition for the target present behind the stopped vehicle, among the targets detected by the target detecting first unit, less restrictive than the predetermined selection condition for other targets, or unconditionally selects the target present behind the stopped vehicle.