An in-pipe work device comprising at least two movement mechanisms (20a, 20b) connected with each other in a longitudinal direction of a pipe (11) by a flexible tube (15), and a control device (19) for controlling the movement mechanisms (20a, 20b), the movement mechanisms (20a, 20b) including a body (21) connected to the flexible tube (15), a guide member (22) installed on the body (21) such that the guide member (22) is slidable in an axial direction, a support leg drive mechanism (24) provided on the guide member (22) and having a support leg (23) movable in a radial direction of the pipe (11), for pressing the support leg (23) against an inner wall of the pipe (11), thereby to hold the guide member (22) kept unmovable in an axis direction of the pipe (11), a slide mechanism (25) for relatively sliding the guide member (22) and the body (21), with the support leg (23) pressed against the inner wall of the pipe (11), thereby to slide the body (21) in the axis direction of the pipe (11), wherein the control device (19) controls the in-pipe movement device so as to move in a pipe (11) by itself, by sequentially operating the plurality of movement mechanism (20a, 20b) in a predetermined order.