N‐Heterocyclic carbenes (NHCs), which react with the surface of Au electrodes, have been successfully applied in pentacene transistors. With the application of NHCs, the charge‐carrier mobility of pentacene transistors increased by five times, while the contact resistance at the pentacene–Au interface was reduced by 85 %. Even after annealing the NHC–Au electrodes at 200 °C for 2 h before pentacene deposition, the charge‐carrier mobility of the pentacene transistors did not decrease.