To suppress the growth of cancer cells by using hydrazine to lower the oxygen concentration necessary for the division of cancer cells having abnormally high division frequency compared with normal cells while keeping the concentration of hydrazine as low as possible to prevent the suppression of the division of normal cells.

Hydrazine is diluted with physiological saline water and administered to cancer cell as a carcinostatic agent. The concentration of hydrazine is set between the estimated minimum concentration to inhibit the division of cancer cells and the estimated maximum concentration to enable the division of normal cells.