An improved method for pressure-adhering tire building component material is provided which includes the steps of:(1) adhering sidewalls to a first cover;(2) cutting each of the sidewalls at a given portion thereof;(3) provisionally securing a joint portion defined by the cut ends of each of the sidewalls;(4) enfolding a bead portion with a bead edge of the sidewall and entirely pressure-adhering each sidewall to the first cover; and(5) pressure-adhering the joint portion provisionally secured with a machine,wherein the step (5) is carried out separately from a production line in which the steps (1) to (4) are carried out.