Cultural and morphological characters of isolates belonging to an entomogenous Paecilomyces species commonly found in Japan were investigated and compared with the literature. This species has not been recorded in major monographs of this genus, but identified as Paecilomyces cateniannulatus Liang described in 1981 from China. Mycelia on insects and media were pure white, and sometimes produce loose synnemata up to 10 mm. Growth rate of the fungus is moderate. The reverse side of colonies on SDY or MEA media are colorless to light yellow. Phialides are flask shaped with a narrow neck, 3.0–16.1×1.3–3.2 μm, often forming a whorl. Conidia are oval to short cylindrical, 2.1– 4.6×1.3–2.4 μm, arranged in basipital chains. Conidial chains are often irregularly curved and sometimes form a loop. Early stage of the conidiogenous structure of this fungus resembles that of Beauveria, but is distinguished by formation of conidial chains.