Provided are a pneumatic device and a pneumatic jack comprising the pneumatic device. The pneumatic device comprises: an air bladder (61); and an air pump (62) having two air holes (621, 622). The two air holes (621, 622) can selectively open and close an air channel with the air bladder, an air-containing object, or the atmosphere. Alternatively, any one of the air holes can selectively open and close a connection with the air bladder, the air-containing object, or the atmosphere. The two air holes of the air pump (62) can selectively communicate with the air bladder and the air-containing object. When the air bladder or the air-containing object requires inflation, an air inflation source can be used. When the air bladder needs deflation, air is discharged from the air pump automatically. When an air-containing object, such as a swimming buoy, needs deflation, the deflation can be performed automatically by means of the air pump, thereby realizing quick deflation. The invention therefore meets demands from the growing diversity of user requirements.