Abstract: A reusable best-by date indicator incudes a main body, which is made of a transparent material, having a plurality of storages, the main body having a first air vent at one end through which outside air can be drawn in and a second air vents between the storages; a plurality of silica gels, each of which is stored in the storages, respectively, the gels changing their color depending on the degree of moisture absorption; a slidable cover that is placed near the first air vent of the body and can exposes the first air vent by slide; and a double-sided tape attached bonded to the back surface of the body.