A method by which the height of an electronic component sucked and held by a nozzle can be detected with high accuracy and high efficiency is a component height measurement method applied to a mounter (100) equipped with a transfer head (8) having a component-sucking-and-holding nozzle (21), for transferring a component P and mounting the component P onto a board (3), and includes: lowering the component P to within the high-accuracy range of a first line sensor (13) for measuring the height of the component P; and measuring the height of the component P using the first line sensor (13).
