The Dipterous leaf-miner from Geranium, Agromyza nigrescens Hendel, is very widely distributed being known from the entire parts of Europe. The present paper deals with a description of a new subspecies of Agromyza nigrescens from Geranium and a brief note of its biology. The anatomical terms are taken from the studies of S. W. Frost(1936). I wish to express my sincere gratitude to Prof. M. Tokunaga for his kind guidance given on this study. I am very much indebted to Prof. S. W. Frost of the Department of Zoology and Entomology of the Pennsylvania State College and Prof. E. M. Hering of the Berlin Zoological Museum for their valuable informations about A. nigrescens.