A suction disc is configured for abutting against a dressing covering over a wound. The suction disc includes a base plate, a case, a negative pressure, a first sensing device and a second sensing device. The base plate has a first surface and a second surface opposite to each other. The first surface abuts against the dressing. The base plate has a first opening and a second opening respectively communicating with the first surface. The case has a first chamber and a second chamber. The case communicates with the second surface. The first chamber communicates with the first opening. The second chamber communicates with the second opening. The negative pressure device communicates with the second chamber. The negative pressure device provides a negative pressure to the second chamber. The first sensing device communicates with the first chamber. The second sensing device communicates with the second chamber.