Refrigerator and control method thereof

A refrigerator (10) includes: a refrigerating compartment (12); a small refrigerating chamber (20) formed by partitioning the interior of the refrigerating chamber (12); a small refrigerating chamber temperature sensor (22) for measuring the indoor temperature of the small refrigerating chamber (20); a cooling chamber (115) that cools the air blown to the small refrigerating chamber (12) by means of a cooler (116); a heating part (117) configured to defrost the cooler (116) by heating; a blower (25) that blows air from the cooling chamber (115) to the refrigerating chamber (12); and a calculation control unit (26). Further, the calculation control unit (26) performs a cooling cycle in which the cooler (116) and the blower (25) are operated such that the indoor temperature of the small cold storage compartment (20) measured by the small cold storage compartment temperature sensor (22) is equal to or less than a first upper limit temperature and equal to or greater than a first lower limit temperature, and the