PURPOSE: A paper cup with an availability determining unit is provided to allow hygienic storage of the cup and to enable a user to easily recognize sales volume. CONSTITUTION: A paper cup with an availability determining unit comprises a cup(10), and a discoloring thread(20) which is adhered to the inner side of the cup and is discolored when the inner side of the cup receives moisture. The discoloring thread is adhered to the inner surface of the cup by an adhesive. The discoloring chamber is formed by dipping a thread in juice of litmus moss.
