An electrode bonding method according to the present invention includes: a plasma cleaning step of irradiating an electrode surface (3) to be cleaned of at least either one of a part (1), such as a semiconductor device, and a substrate (10) with atmospheric pressure plasma (8) for cleaning; an inert gas atmosphere maintaining step of covering the electrode surface (3) to be cleaned and its vicinity with a first inert gas (4) before the irradiation of the atmospheric pressure plasma (8) is ended, and maintaining that state even thereafter; and a bonding step of bonding an electrode of the part (1) and an electrode on the substrate (10) before the inert gas atmosphere maintaining step is ended. The electrode surface (3) is thereby plasma-cleaned without the possibility of damaging the part (1) to be bonded to the substrate (10), and the cleaned state is maintained while bonding the electrodes to provide an electrode bonding state of high bonding force and high reliability.