An object type determination apparatus mounted in a vehicle. In the apparatus, a detection unit detects an object present forward of the vehicle. A height estimation unit estimates a height of the object detected by the detection unit from a road surface. A determination unit uses the estimation result of the height estimation unit to determine, according to one of a plurality of predefined criteria, whether or not the object is an object for which a collision avoidance process is performed. A complex environment estimation unit estimates a likelihood that a complex environment is present forward of the vehicle. A criterion selection unit selects the one of the plurality of predefined criteria used by the determination unit on the basis of the estimation result of the complex environment estimation unit.