A combination chair includes a chair body, which has a front opening, a hard bottom board supported on the flexible bottom panel of the chair body, two reinforcing plates detachably connected between the front and back panels of the chair body by hook and loop materials, a hard top board supported on the reinforcing plates, a cover member covered on the chair body for a person to sit thereon, and a storage box inserted through the front opening into the inside of the chair body between the two reinforcing plates for keeping things.