A resistance spot welding method of squeezing parts to be welded, which are a plurality of overlapping metal sheets, by a pair of electrodes and passing a current while applying an electrode force to join the parts to be welded comprises: a first step of passing a current by constant current control to form a fusion zone having a diameter of not less than 2√{square root over (t)}, expressed in mm, between the metal sheets, where t, expressed in mm, is a sheet thickness of a thinnest metal sheet of the metal sheets; a second step of cooling the fusion zone to have a diameter of not greater than 80% of D, where D, expressed in mm, is a diameter of the fusion zone formed in the first step; and a third step of performing adaptive control welding by controlling a current passage amount according to a target that is set.