Provided is a fixing device, the heat generation amount of which can be obtained with a smaller amount of a microwave absorbing material. As a result, the start-up (warm-up) time for achieving a fixing temperature can be shortened without impairing characteristics such as flexibility, releasing property, and durability. The fixing device includes a heating member; a pressurizing member; and a microwave generating unit. It is configured to fix an unfixed toner on a recording material by passing the recording material through a nip formed between the heating member and the pressurizing member. The heating member includes a heat generating layer for generating heat with microwaves generated by the microwave generating unit. The heat generating layer contains a high molecular compound and a carbon fiber having an average fiber diameter of 80-150 nm, an average fiber length of 6-10 μm, and an absorption peak in a Raman spectrum resulting from a graphite structure.