Penicillium digitatum SACCARD, P. italicum WEHMER, Botrytis cinerae PERSOON and Sclerotinia sclerotiorum MASSE. were the main storage diseases on the cold injured mandarin at Jeju in 1975. The losses observed through the materials used were $18.3\%$ which consists of $8.1\%$ by diseases and $10.2\%$ by water rot as the result of cold and snow damages at harvest stage in Jeju. The total amount of damages estimated at shipping stage were 915M/T in value of 135 million Won from the rot waste of 675M/T by the end of 1975. Since cold injury is known as the main factor of the fruit rot, shipping and storage process as well as disease control measures are discussed.