To provide a guide device of a sliding door capable of decreasing the number of parts to prevent looseness of the sliding door at a low cost, and being used for comparatively light-weighted sliding doors such as a Japanese sliding door, a sliding paper door and the like.

A deformable disk 1 having elasticity is pivoted on an upper end face 30 of the sliding door 2 to turn on the vertical axis, and the disk 1 is inserted so that there is little play in a guide groove 5 of a lintel 4 in which the upper end part 3 of the sliding door 2 is slidably engaged.