PURPOSE: To provide a electric parts arranging device and a automatic arranging method, which can automatically arrange parts by taking a heat radiation characteristic of parts into consideration.

CONSTITUTION: The automatic electric parts arranging device is provided with a data base store part 8 for storing information required for an arrangement design, an arrangement object parts selecting part 4 for considering a connecting relation of parts and its electric characteristic, and selecting arrangement object parts to be arranged in the next time, an arrangement determining part 5 for determining an arrangement position on a printed board by considering a connecting relation of the arrangement object parts and its electric characteristic, an unarranged area inspecting part 6 for retrieving an unarranged area surrounded by a parts group consisting of the arrangement object parts and arranged parts by arranging the arrangement object parts in a position determined by the arrangement determining part 5, and inspecting whether an area of this unarranged area exists in a designated range or not, and an inhibited area determining part 7 for setting a limit value against height of parts arranged in the unarranged area, and designating this unarranged area as a height limit area, in the case the area of the unarranged area exists in the designated range by the unarranged area inspecting part 6.