PURPOSE: To facilitate the shift of a moving form device, improve workability, and salve labor by providing a boom on a side frame, and setting a form so that the lining state of the inner face of an excavated tunnel coincides with the excavation state.

CONSTITUTION: A side frame 4 is provided in front of a form 1, split slide side plates 5 with side plate cylinders 8 are arranged on the front face of the side frame 4, and slide booms 13, 14 are arranged to support the side frame 4. A rotary mechanism such as a frame rotating hydraulic motor 12, a pinion 11, and a gear is fitted at the tip of the boom 13, and the slide side plates 5 are set along the excavation face of a tunnel. The form 1 is set at the preset position, a lifting cylinder 27 is lowered, and the side frame tilting cylinder 3 of the slide boom 13 is pulled to set the side frame 4. The hydraulic motor 12 is operated, slide side plates 5 are matched with the inclination of excavated irregular faces, and ready-mixed concrete containing an accelerating agent is placed. The side frame 4 is divided to provide multiple slide side plates 5, and multiple slide booms 13, 14 are provided to support them.