A series of experiments on the carbon-resin system thick film resistors of low temperature firing type has been conducted under various conditions of volume mixing ratio of carbon black particle (CB) and carbon fiber (CF) dispersed in binder resin in order to obtain resistors with any desired resistivity as well as with excellent electrical characteristics. From the experimental results optimum conditions in volume ratio of CB against CF, (CB/CF), and volume fraction of CB+CF against total resistor materials including binder resin, , have been found to minimize temperature coefficient (TCR), current noise index (NI) and variation of resistance in heat cycle (VHC).