PURPOSE: To dispense with displacement of a concrete placing pipe so as to enhance construction efficiency by pressurizing concrete placed between an inner form and the natural ground by means of a press ring movable in the axial direction of a shield.

CONSTITUTION: Openings 11 corresponding in the number to concrete placing pipes 4 are provided penetrating in the axial direction of a shield at proper places of a press ring 1, which is formed movable in the axial direction of the shield by means of a press jack. A tip 42 of the concrete placing pipe 4 is inserted and arranged in the opening 11 of the press ring 1 so as to be positioned within the opening 11 even when the press ring 1 is at a position most moved to the placed concrete side. A tip of a push out rod 6 is inserted from a tail end 43 of the concrete placing pipe 4 into the pipe 4 and moved to the tip 42 side so that remaining concrete in the pipe 4 can be pushed out to between an inner form and the natural ground and troublesome work to disassemble piping for cleaning can be dispensed with.