To horizontally accurately fit and adjust the sliding door body of an indoor sliding door.

An outer frame is movably provided on a case 10 in the width direction, a sash roller 8 and two projection pieces 25 are provided on an inner frame provided on the outer frame to be made a sash roller device 7, the case 10 is attached to a sliding door body 6, the sash roller 8 is brought into contact with the bottom part 4c of a guide recess groove 4 and the two projection pieces 4a, 4b are brought into contact with both the sides 4a, 4b of a guide recess groove 43 to be made an indoor sliding door 5. The sliding door 6 is moved in the width direction of the guide recess groove 4 together with the case 10 for the sash roller 8 and the two projection pieces 25 and horizontally accurate fitting can be adjusted by moving the outer frame for the case 10 in the width direction.