The present invention is a method and an apparatus for preventing the entrance of an unmanned dump truck, so that an interference and a collision between the unmanned dump trucks and a working vehicle in the working area are prevented. In the method, an unmanned dump truck (3) enters the working area (91) only when another dump truck (3a) is not in the working area (91) and the working vehicle (92) in the working area (91) issues an entrance permission command. The apparatus includes entrance permission means (22), provided on the working vehicle (92), and computing means (11), for outputting a control command thus permitting the unmanned dump truck (3) to enter only when another dump truck (3a) is not in the working area (91) and an entrance permission command is inputted into the apparatus.