Ti(C,N)-based ceramics that contained NbC, TaC, and WC were exposed at 1373 K in air for 10 h to study the effect of these meatal carbides on the oxidation resistance. The addition of 10 mol% of NbC and 10 mol% of TaC to TI(C,N) ceramics improved the oxidation resistance, whereas additions of 10 mol% of WC worsened the oxidation resistance. Weight gain due to the oxidation of TI(C,N) ceramics with added WC varied in a complicated way, relative to the amount of WC that was involved. There was a competition between weight gain due to the oxidation and weight loss due to the volatile tungsten oxide.