To provide an instrument for regulating a temperature of a baby bottle which can rapidly cool the baby bottle containing a high-temperature milk down to a temperature suitable for lactation, and a method for regulating the temperature of the milk bottle using the instrument.

The instrument for regulating the temperature of the milk bottle comprises: a cylindrical frame 12 which has a plurality of openings 20 on its peripheral wall and is formed to house the baby bottle inside; a refrigerant-holding member 16 for installing the refrigerant in such a way of surrounding the cylindrical frame 12; and an outer container 10 which can house both the cylindrical frame to house the baby bottle and the refrigerant-holding member. Water is poured up to a height above a level of the high-temperature milk in the baby bottle in the outer container, thereby the temperature of the milk can be regulated to be suitable for lactation.