The subgenus Micrundvena Ashmead of the genus Andrena of Japan is revised and eleven species are recognized. Five of them are new to the Japanese fauna. In this paper (Part I) seven species are treated, including two new species, Andrena (Miwandrena) munakatai and A. (Micrandrena) hanedai. The male of A. (Micrandrena) falsijicissima Hirashima is described for the first time. The distributional map, floral records, and flight records of each species are presented.