The migration of blow flies from the lowland to the highland was investigated at Mts. Tateyama in Chubu Sangaku National Park in 1985 and 1986. To capture the adult flies, 30 bait-traps were set between altitudes of 420 and 900m along the valley of Shomyo River at the foot of Mts. Tateyama. The capturing period was from May 8 to June 12 in 1985 and from April 30 to July 2 in 1986. The dominant species were Calliphora nigribarbis and C. vomitoria. A total of 8,909 and 13,990 adults was marked and released in 1985 and 1986,respectively, at an altitude of 660m. Bait-traps of a permanent type were set at altitudes of 1,000,1,500,2,000,2,300,2,500 and 2,700m for continuous recapturing. Eighteen and 17 females were recaptured in 1985 and 1986,respectively, by these traps of higher than 2,000m. All of them were C. vomitoria. Only one marked female of C. nigribarbis was recaptured in 1985 at 1,500m. In 1986 additional recapturing was conducted by the bait-traps at 420 to 900m along the valley of Shomyo River. C. vomitoria flies were never recaptured at lower altitudes than the release place. On the other hand, C. nigribarbis flies were recaptured at both higher and lower altitudes than the release place. These results indicate that C. vomitoria has a strong tendency to migrate to the alpine and subalpine zones in early summer and may stay there during the summer season, whereas C. nigribarbis does not have such steady migration pattern.