An expansive filler joint includes: a securing hollow body (1) embedded in a jointing end (3, 3) of forming concrete (K) or concrete segmental products (K', K'), the securing hollow body (1) made of a rigid material and having a closure means (2) disposed at a plurality of side ends of the securing hollow body (1), an expansive filler (4) filling the securing hollow body (1), and reinforcing bars (5, 5) inserted into the securing hollow body through the closure means (2) and opposed to each other, wherein the opposed reinforcing bars (5, 5) are secured by prestress and pressure of expansion of the filler (4). A reinforcing bar jointing process includes: embedding a securing hollow body (1) in a jointing end (3, 3) of forming concrete (K) or concrete segmental products (K', K'), the securing hollow body (1) made of a rigid material, providing a closure means (2) disposed on an opening (1a) formed at a side end of the securing hollow body (1), filling an expansive filler (4) into the securing hollow body (1) through the closure means (2), and inserting at least one of reinforcing bars (5, 5) opposed to each other into the securing hollow body (1) through the closure means (2), wherein the reinforcing bars (5, 5) are secured to each other by prestress and pressure of expansion of the filler (4).
