A mouthpiece for a breathalyzer. A body (20) includes a breath inlet (22) and a breath outlet (24) through which breath enters and exits. A breathalyzer fitting part (30) protrudes from the outer circumference of the body (20), and is fitted into a breathalyzer (10). A transparent hollow breath indicator (40) is disposed on the body (20) so as to be perpendicular to the lengthwise direction of the body (20). A breath flow hole (50) provided on the body (20) allows the breath indicator (40) and the body (20) to communicate with each other such that the breath that has entered through the breath inlet (22) moves into the breath indicator (40). A breath indicator ball (60) is movable upward and downward inside the breath indicator (40) so as to be lifted up by the breath that has entered the breath indicator (40) through the breath flow hole (50).
