PURPOSE: To freely open or close a door at an optional position by providing multiple recessed grooves inside an outer ring, and providing a circular support plate with bearing members and a hooking clutch pressing the bearing members to the recessed grooves for hooking in both directions.

CONSTITUTION: A sash roller 1 is constituted with an outer ring 2 forming a rail hooking groove, a support shaft 3 and a two-way hooking clutch 4. The clutch 4 is constituted of an outer tube material 41, a bearing 42, a bearing 43, and a pressing body 46 consisting of a pressing pin 44 and a holder 45, and the clutch 4 is located at the unhooked position during rotating movement. A through hole 42a penetrated by the support shaft 3 is bored on the bearing supporter 42, a recessed groove 42b formed with retreat grooves 42d, 43e are formed, the pressing body 46 is hooked by the pressing pressure, and the hooking is released when the torque is applied in the opposite direction. A sliding door can be fully opened, fully closed, or opened or closed at an optional position.