The HER2‐targeting near‐infrared photoimmunotherapy (NIR‐PIT) using an anti‐HER2 antibody, trastuzumab, induced HER2‐expressing SCLC cells death, and efficacy of this therapy was significantly higher in SBC‐3/CDDP than in SBC‐3 in vitro and in vivo. This evidence concerns the gene ERBB2 and small cell lung carcinoma.