Tacrolimus is thought to be involved in the development of malignant tumors including lung carcinoma. A 43-year-old woman diagnosed with systemic lupus erythematosus started tacrolimus. Four months later follow-up computed tomography showed a newly appeared irregular mass in her right lower lobe and enlarged mediastinal and supraclavicular lymph nodes. A pathological review of the mediastinal lymph node specimens obtained by endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) showed poorly differentiated adenocarcinoma including signet-ring cells, which indicated lung carcinoma (cT4N3M0, cStage IIIC). Panel testing using AmoyDx® revealed the c-ros oncogene 1 (ROS1) fusion gene. After crizotinib was administered, the carcinoma shrank markedly. Lung carcinoma appeared in a young woman after the introduction of tacrolimus and rapidly increased over a very short time. To monitor the possible development of lung carcinoma, careful follow-up is important for patients receiving tacrolimus.