To effectively utilize a charcoal or a tire charcoal and obtain a baked product capable of further promoting recycle by compounding and kneading a clay or its weathered zone clay with the charcoal or tire charcoal and limestone, preparing a charcoal-containing mixed clay, molding and baking the resultant mixture.

A clay or its weathered zone clay or a weathered zone clay of limestone, specifically Ryukyu gray clay or its weathered zone clay or a weathered zone soil of Ryukyu limestone is sufficiently dried, pulverized and passed through a 14- to a 16-mesh sieve. The undersize in an amount of 20-40 wt.% is compounded and kneaded with an undersize in an amount of 20-40 wt.% obtained by passing a charcoal prepared by carrying out the carbonizing treatment of old wood, sawdust, a coconut shell, etc., or a tire charcoal obtained by the carbonizing treatment of a waste tire through a 22-mesh to a 10-mm sieve according to uses and an undersize in an amount of 10-20 wt.% prepared by prebaking limestone, specifically the Ryukyu limestone, pulverizing the prebaked Ryukyu limestone and passing the pulverized Ryukyu limestone through a 22- to a 23-mesh sieve to prepare a charcoal-containing mixed clay. The resultant mixed clay is then molded into a clay molded product of a prescribed shape, dried and subsequently baked at 500-800°C temperature to afford the baked product.