To obtain activated or calcified porous calcined shell powder enhanced in the pulverizing calcination performance of the shells and diversified in the uses by calcining roughly crushed shells at a proper calcination temperature with stirring.

This activated porous dry calcined shell powder is obtained by calcining roughly crushed shells at a calcination temperature controlled to approximately 300-800°C with agitation. The another objective dry and porous calcified shell powder is obtained by calcining roughly crushed shells at a calcination temperature controlled to approximately 850-1,150°C with agitation. The device for calcining shells is provided with a roughly crushing machine 2 having a conveyer 3 for feeding shells, a rotary kiln 5 for continuously stirring and calcining the roughly crushed shells into the activated calcined shell powder or the calicified shell powder, and a conveyer 6 used for feeding the powder into a storage tank 7 and simultaneously for cooling the powder.