PURPOSE: To keep a cement mortar raw material in a raw material tank at a given temperature level.

CONSTITUTION: When the temperature of a cement mortar raw material 70 stored in a raw material tank 10 is measured to be higher than a set temperature by a temperature sensor 61, an on-off valve 54 of a cooling water pipe 52 is opened by a temperature controller 62 to feed cooling water between the raw material tank 10 and a jacket 20. On the other hand, when the temperature of the cement mortar raw material 70 in the raw material tank 10 is measured to be lower than the set temperature by the temperature sensor 61, an on-off valve 55 of a steam pipe 53 is opened by the temperature controller 62 to feed steam between the raw material tank and the jacket.