To provide a bag integrated with a chair, which allows a user to be seated stably even in a crowded place and which is easy to use or carry, and to provide and a bag detachable from a chair.

The bag integrated with chair 1 has two leg parts 2 placed at an interval and configured extendable, support parts 3 provided at lower both ends and the upper ends of the two leg parts 2, and a seat part 4 provided at the upper support parts. Also, the bag 8 detachable from a chair has: a seat part 4 which is connected to an extendable leg part 2 and the upper end of the leg part, and a support part 3 which is fixed at the lower end; and a chair of the seat part, rotatable within a horizontal plain face with the leg part serving as its axis, is detachable. When being seated by using both, the leg parts 2 are extended to the appropriate length before being seated on the seat part 4. As for the latter, the chair can be removed and can be installed at a seat setting part of another bag detachable from a chair.