A forging method for upsetting end portions of a raw material as diameter expansion scheduled portions includes: providing an upsetting apparatus having a fixing die, guides each having an insertion passage for inserting and holding an end portion of the raw material in a buckling preventing state, and punches each for axially pressing the end portion of the raw material inserted in and held by the insertion passage; inserting end portions of the raw material with the end portions protruded from the fixing die into the insertion passages; and moving the guides in direction opposite to moving direction of the punches such that length of exposed portion of the raw material becomes equal to or less than buckling limit length at cross-sectional area of the exposed portion of the raw material while simultaneously axially pressing the end portions of the raw material with the punches.