To make it possible to construct a manhole with a reaction force easily available on a construction site by pressing a skeleton block loaded on a board for settlement prevention into an underground area with a jack provided on a press-in frame where a reaction load, such as heavy equipment and excavating the soil inside the skeleton block.

An obstacle of immersion work is eliminated and a skeleton block 3a, on which a cutting edge is set up, is loaded on a bottom board so that the cutting edge may come horizontally in an excavated hole, thereby backfilling the surrounding area. Then, the bottom board is removed and a press-in frame 4 is set up so that a reaction load, such as heavy equipment may be loaded on a stay 5. A push frame 6 is loaded on the skeleton block 3a which is pressed in underground with a jack 7, thereby repeating excavation so that the whole skeleton block 3a may be immersed. When the excavation comes to an end, the heavy equipment or the press-in frame 4 or the like is removed and concrete is placed. This construction makes it possible to construct a manhole with a simple device using a reaction force which is easily available.