Receptor functions of metal‐carbonates for solid‐electrolyte impedancemetric gas sensor based on Li‐ionic conductor (Li1.5Al0.5Ti1.5[PO4]3) were studied. It was revealed that sensors attached with metal‐carbonate receptors rarely responded to CO2, on the contrary, they well responded to NOx. In addition, it was found that the responses to NOx differed depending on the metal‐carbonates. The sensor using the binary carbonate (Li2CO3 + CaCO3) receptor showed high NO2 sensitivity and different NO responses at 300 °C, 50 Hz, i.e., other devices responded to NO2 and NO with same direction, while the binary carbonates (Li2CO3 + CaCO3) system responded to NO2 and NO in the opposite direction, which should give selective detection among NO and NO2. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.