To provide a bag capable of favorably accelerating the execution of work by allowing a working person in a non-territorial office to favorably bring requisites to his/her own seat and quickly take them away when leaving the seat.

This bag is favorably applied to a chair which is provided with a baggage placing surface C75 between a support base C3 and a seat C5, and is formed with a baggage storage space C77 for extractably storing the bag 1 between the baggage placing surface C75 and the back face of the seat C5. In concrete terms, this bag 1 includes: a bag body 3 formed into a flat plate shape; a pair of grips 5 provided on both ends of the bag body 3; and a display section 7 provided on the upper face side of the bag body 3 and displaying owner information for displaying the owner.