The task of the present study is to elucidate the reality of labor hygiene in Colonial Korea by reviewing the employees’ health conditions in the Korean National Posts and Telecommunications (KNPT) and the KNPT authorities’ measures taken against it. A colonial employment structure, which emphasized the role of ethnic Japanese in the division of labor system, was built in to the KNPT. Ethnic Koreans were assigned mainly to the lower classes of the hierarchical system and relatively to dangerous tasks with the wages amounted to only more than half of those of the Japanese. Nevertheless, the health indexes, e.g. morbidity rate, death rate and turnover rate from diseases of the Koreans were lower than those of the Japanese, which means that the physical conditions of Koreans were better than those of Japanese. Even though Japanese employees often worked indoors and lived communally after work, the very comfortable life style was the cause that increased the likelihood of their exposure to infectious diseases. To cope with these situations, KNPT authorizes established the Field Worker Relief Association and strengthen the part-time doctor system. However, while the morbidity rate showed an upward trend from the mid-1930s, the mortality rate and the disease turnover rate were not high. ‘The good body-making policy’ of KNPT authorizes was not to decrease the diseases but to hold down the deaths and retires concomitant with the increase of diseases.