Electronic part mounting device and electronic part mounting method

An electronic part mounting device and method enabling reduction of frequency of work needed when the type of an electronic part is changed and improvement of the productivity. In a part mounting work, chips of types A, B, and C are taken out of a part supply unit by means of a single mounting head and are mounted on two substrates held by first and second lanes, at a previous substrate mounting step of mounting a part on a previous substrate previously loaded out of substrates, when a succeeding substrates loaded subsequently becomes mountable before the previous substrate mounting step is ended, a succeeding substrate mounting step is started by handling the chip to be mounted on the previous substrate as a mounting start part at this timing, and the previous substrate mounting step whose mounting is not completed is continued. With this, the frequency of work needed when the type of part is changed, such as a nozzle interchange, can be reduced.