To reduce the friction force of a pile peripheral face by cement milk to press piles in by pressing the pile into ground while the cement milk is jetted from the edge part of the pile.

The pile 12 is pressed in ground while the cement milk 1 is jetted from the tip part of the pile 12. Blending of the using cement milk preferably uses the water and cement ratio of 60-150% in the weight ratio of water and cement. Thus, the peripheral ground of the piles is disturbed as well as a conventional water jet by utilizing the flowing time band of the cement milk 1, and the pile 12 can be pressed-in in a state where the friction force of the pile peripheral face is reduced. Since the piles need not be large-sized or it need not deal with the increase of the number of the piles, the piles can be economically pressed in and erected in a single process in pile foundation comparatively large in support force by the comparatively small-sized piles without increasing the construction cost of the pile foundation.