A one-way clutch of an inscribed gear type has a cylindrical outer member having an inner gear at an inner circumference thereof; an inner member rotatably disposed in an inside space of the inner gear, and having gear receivers and a lock edge on one side in a circumferential direction of the gear receiver; and a planetary gear received rollably in each of the gear receivers to mesh with the inner gear. Shafts are projecting from both ends of the planetary gear, and bearing recesses are formed on the gear receiver to receive the shaft. By the engagement between the shafts and the bearing recesses, the planetary gear allows a circumferential displacement within a predetermined range with respect to the inner member required for engaging to or disengaging from the lock edge, and the planetary gear is prohibited from being displaced inward in a radial direction of the inner member.