To provide a spacer excellent in handleability capable of being easily packaged for reducing the waste of packaging material which usually arises in a large amount during the construction of a house, and increasing efficiencies for transportation and storage by reducing the packaged volume thereof.

The spacer for concrete forms has outer and inner regulating pieces on the right and left sides to form a form fitting part for maintaining two concrete forms in a predetermined spaced relationship. A locking piece consisting of a curved part and a pressing part located above it is provided at the top of the outer regulating piece. When the spacers are stacked one above the other, the locking pieces are bent outwards so that the portion of the upper spacer between the outer regulating pieces can be inserted between the locking pieces of the lower spacer. The front ends of the outer or inner regulating pieces of the lower spacer support the bottom of the upper spacer. Projecting and recessed fitting parts are provided which fit between the opposing parts of the upper and lower spacers to restrict lateral movement of the spacers.