The invention relates to the technical field of washing machines and discloses a treating agent adding device and a washing machine. The treating agent adding device comprises a treating agent box andis characterized in that the treating agent box is connected with an adding mechanism and provided with a filling port, the filling port is provided with a cover, a sealing membrane is mounted on thetreating agent box and/or the cover, the sealing membrane is provided with a ventilation notch, and the ventilation notch can be opened under the effect of air pressure. The treating agent adding device has the advantages that the filling port of the treating agent box is provided with the cover, the sealing membrane is arranged on the treating agent box and/or the cover, and accordingly treatingagent box sealing is achieved effectively, water in the treating agent box is prevented from being evaporated, a treating agent in the treating agent box can be prevented from being dried and coagulated for a long time, failure of the automatic adding function of the washing machine and treating agent box cleaning difficulty are avoided, air pressure balance inside and outside the treating agentbox is achieved, and the sucking ability of the adding mechanism is prevented from being affected by excessively large negative pressure inside the treating agent box.