interposed between and transferred between the heating roller tr of the induction heating roller 21 and the pressure roller 22 and toner 24 to be applied with heat from the heating roller tr to be melt to carry out thermal fixing of toner 24 fig2 is a schematic cross sectional view of a copying machine of a preferred embodiment serving as an image forming apparatus the image forming apparatus is shown including a reader unit 31 an image forming unit 32 a fixing unit 33 and a case 34 the reader unit 31 optically reads out image pattern of original sheet to produce an image signal indicative thereof the image forming unit 32 responds to the image signal for producing electrostatic charge of a latent image on a photosensitive drum 32 a with toner being adhered to the electrostatic charge of the latent image to form reversed image pattern which in turn is transferred onto record medium such as a paper sheet to form a desired image pattern the fixing unit 33 has a structure shown in fig2 for thermally melting toner which is transferred to record medium to cause toner to be thermally fixed thereto the case 34 conceals the various component parts discussed.