To improve the adhesiveness to a spacer so as to be fixed within concrete even after solidification, and to improve the durability of a structure by forming a spacer for holding a reinforcement or aggregate prior to concrete placing by use of ceramic containing a prescribed quantity of mullite.

A work spacer is formed by mixing 20-40 wt.% of chamotte with 70-80 wt.% of alumino silicate, molding the mixture into a prescribed dimensional form by use of a metal mold, and then baking it at 1250-1350°C to provide a ceramic spacer having a low water absorption of 0.5% or less. The alkali component in the work spacer is set to 2-6 wt.% in order to suppress the deterioration of reinforcements by alkali and to improve the durability of a structure. According to this, a ceramic spacer having low water absorption, excellent in strength and adhesion with concrete, and capable of improving the durability of concrete structure can be provided.