Abstract: A filter for a hemodialysis apparatus is provided, which includes: a first cover member, a second cover member coupled to the first cover member, and a membrane disposed in a chamber of the first cover member. The membrane has a first membrane layer and two second membrane layers respectively bonded to two opposite sides of the first membrane layer. A plurality of first ridges and second ridges are formed on a side surface of the second cover member, spaced apart from one another and having different widths so as to increase the friction force. The non-directional three-layer structure of the membrane has a high water pressure resistance, greatly reduces the chance of fluid leakage, and avoids erroneous disposition.