Disclosed are a composition for a sanitary ware body for use in slip casting, possessing excellent long-term storage stability, transportability and slurry regeneration, a production process of the same, and a production process of a sanitary ware using the composition for a sanitary ware body. This composition for a sanitary ware body comprises agglomerate of a raw material powder for said sanitary ware body and has a water content of 0 (zero) to 25% by weight and a 50% average particle diameter of 1 to 15 .mu.m on a number basis of the powder. A slurry of a raw material for a sanitary ware body for use in slip casting can be prepared by adding water to the composition for a sanitary ware body and stirring the mixture.