PURPOSE: To prevent the generation of chips, etc. by a method wherein a guide body with a guiding hole for a lead wire, an air hole for flowing air and an air curtain slit is arranged to an upper section of a jig to which a semiconductor pellet is set, the lead wire is let fall and an electronic part is assembled.

CONSTITUTION: A lead wire 2 is inserted into a supporting hole 13 of a jig 12, and a pellet 5 of a DHD type diode is placed through a heat sink 4. A glass tube is glued so as to surround the pellet 5. To an upper section of the jig 12, on the other hand, a guide body 14 is disposed which has a guiding hole 15 concentric to the supporting hole 13. An air hole 16 crossing at right angles with the guiding hole is formed to a lower section of the guide body, and connected to an air blowing source and a vacuum source, and purified air is ventilated. An air slit 17 is made up to one end of the air hole. A lead wire 1 is let fall from the guiding hole, introduced into the glass tube, and glued. Thus, the lead wires are kept clean, the generation of foreign matters such as chips is prevented and reliability is increased in an automatic assembling machine for electronic parts.