PURPOSE: To efficiently place concrete by a horizontal placing method and thereafter to turn a formwork sideways and to surely perform defoaming by using a lateral turning device constituting of a lateral turning means for turning the formwork sideways and a fixing means for fixing the lateral turning means and the formwork.

CONSTITUTION: A lateral turning means is constituted by arranging four pieces of lateral turning rollers 2 on a floor face in the front and the rear in the right and the left at the specified intervals so as to direct rotary shafts 34 in the conveyance direction of a formwork 1. A lateral turning body 23 is placed thereon. A pair of front and rear semi-circular arclike lateral turning rails are horizontally set between the opposite lateral turning rollers 22. The lateral turning body 23 is turned sideways on the lateral turning rollers 22 at 90 degrees in the transfer direction of the formwork. A fixing means 21 fixes a rectangular box-type formworklike fixed frame 40 to the lateral turning body 23. The force-pinching part 41 of the formwork is provided thereon. Concrete is placed in the formwork by a horizontal placing method. The formwork is closed and carried into the fixed frame 40, pressed and pinched by the force-pinching part 41 of the formwork and turned sideways at 90 degrees.