To prevent a stepwise sudden change in a detecting result at sensor switching time in an object detecting device for a moving body having a long distance sensor and a abort distance sensor.

When switched to a short distance sensor using mode from a long distance sensor using mode, a decided inter-vehicle distance d is interpolated on the basis of a long distance sensor distance value df detected by the long distance sensor and a short distance sensor distance value dn detected by the short distance sensor for a prescribed period, and is gradually transferred to the short distance sensor distance value dn from the long distance sensor distance value df (Step S12), and a deciding relative speed v is interpolated on the basis of a long distance sensor relative speed value detected by the long distance sensor and a short distance sensor relative speed value vn detected by the short distance sensor, and is gradually transferred to the short distance sensor relative speed value vn from the long distance sensor relative speed value vf (Step S13).