Herein are provided a fixing device for use in toner processes such as electrophotography and the like which comprises a thermal fixing roll (12) used after trans­fer of toner, a compression bonding roll (13) and a heat generating medium for said thermal fixing roll which is a composite ceramic prepared by adding an organic binder to a powder of metallic silicon or ferrosilicon, heating and kneading the resulting mixture, forming the mixture into a formed product, removing the organic binder from the formed product at an elevated temperature and heating and sintering the formed product in an atmosphere of nitrogenating gas to connect the insulating particles and electroconductive particles of Si₃N₄, Si₂N₂O or SiO₂ formed from the silicon and different in electrical resistivity from one another with whiskers formed from the silicon, and a recording device (8-11,14) utilizing said fixing device.