A DNA comprising a 609 bp base sequence from -559 to +50 when the first base sequence of exon 1 of the midkine gene, a human retinoic acid-responsive growth/differentiation factor was set as +1, or a DNA comprising a 251 bp base sequence from -213 to +38 when the transcription initiation point of the c-erbB-2 gene belonging to the EGF receptor family and having a tyrosine kinase activity was set as +1 has a tumor-specific transcription activity, and the promoter activity thereof is high, and therefore is very important as a tumor-specific promoter for use in the suicide gene therapy that combines the use of a gene for a drug metabolizing enzyme and a prodrug for cancer therapy, the gene therapy of cancer using an expression vector that contains a gene encoding a cytokine, and the gene therapy of cancer using an oncolytic virus.