A chair includes a backrest frame, an armrest frame detachably mounted on the backrest frame and a seat frame detachably mounted between the backrest frame and the armrest frame. Thus, the seat frame and the backrest frame are combined together easily and quickly so that a user can assemble and disassemble the chair by himself without needing aid of any hand tool, thereby facilitating the user assembling and disassembling the chair. In addition, the armrest frame, the seat frame and the backrest frame are detached from and laminated with each other before assembly so as to reduce the whole volume of the chair and to decrease the cost of packaging, storage and transportation of the chair.