PURPOSE: To obtain a bipolar transistor in which a junction capacity between a base and a collector and a base resistance are reduced by forming a contact hole for forming the base electrode of the transistor in a self-alignment with a separating oxide film.

CONSTITUTION: A silicon oxide film 11 and a silicon nitride film 12 are formed as first insulating films on an N-type epitaxial layer 10, and a silicon oxide film is sequentially covered as the second insulating film. Then, a mask 14 is formed, the films 13, 12 are then removed, and the film 13 is sidewisely etched. Thereafter, the mask 14 is removed, a separating oxide film 15 is formed, the exposed film 12 is then removed, the film 11 directly under the remaining film 13 and the removed film 12 is removed to expose the layer 10, boron is added to an element forming region to form a P-type base region 16. Then, after a first polycrystalline silicon film 17 of 0 is formed, a mask 14A is formed, and an impurity is implanted thereto.