[Problem] To provide a compound that is useful as an active ingredient of a pharmaceutical composition for the treatment of lung cancer. [Solution] The present inventors examined compounds that are useful as an active ingredient of a pharmaceutical composition for the treatment of lung cancer and found that a quinazoline compound exhibits superior G12C-mutant-KRAS inhibiting activity and could be used as a lung-cancer treatment drug, thus arriving at the present invention. The quinazoline compound according to the present invention or a salt thereof could be used as a lung-cancer treatment drug.
