Abstract: A transcriptional inhibitor for human K-ras gene which comprises one or more proteins selected from the group consisting of a protein having the amino acid sequence represented by SEQ ID NO:1, a protein having an amino acid sequence derived from the amino acid sequence represented by SEQ ID NO:1 by substitution, deletion or addition of one to several amino acids and having an activity of inhibiting the transcription of human K-ras gene, and partial fragment proteins thereof having an activity of inhibiting the transcription of human K-ras gene. This transcriptional inhibitor for human K-ras gene specifically inhibits the transcription and expression of K-ras gene, which is an oncogene, in a human cancer cell. Thus, it can inhibit the proliferation of cancer cells and induce the reversion of cancer cells into normal cells, which makes it usable as an anticancer agent with little side effects on normal cells.