The present invention relates to a method and an apparatus for mounting a part at a specific position, particularly a chip part onto a substrate such as a printed circuit board, wherein a movable mounting head unit having at least one attracting nozzle unit picks up at least one part from a part supply unit, transfers the part and places same in a detection area of an optical detecting means at a recognition height, said optical detecting means emits parallel light beams for detecting a projected width of the part, the parts are subjected to a recognition process wherein projected width data are obtained under rotation of the part, and the part is mounted at the desired position. In order to determine a recognition height suited for each part quickly and with good accuracy, the method is improved in that optimum recognition height of each part attracted by said nozzle unit is determined by detecting a recognition height range with a projected width of the part that is more than or equal to the reference value and calculating a specified position within said recognition height range as the optimum recognition height of the part. The apparatus is improved in that a determination means is provided for determining whether the projected width of said part is more than or equal to reference value, and in that an operation means is provided for determining a recognition height range in response to an output of the determination means and for calculating a specified position within the recognition height range.