Two species of the pompilid genus Agenioideus occurring in Japan are described: A. (Agenioideus) kokyo and A. (A.) cinctellus. The former is new to science and the latter is recorded from Japan and Taiwan for the first time. A brief summary of the biology of A. cinctellus, distinguishing characters between A. (A.) ishikawai Shimizu, 1989 and its relatives, and a key to all Japanese species of this genus are presented. Psammochares cinctellus f. rufa Haupt, 1938 and A. (A.) pacificus Lelej, 1994 are newly synonymized with A. cinctellus. A new combination is proposed: A. (A.) maculipes (Smith, 1870) (=Pompilus maculipes Smith), which is found in Southeast Asia to South Asia. Agenioideus ishikawai is newly recorded from Korea and China.