One object of the present invention is to provide a method for producing stable isotope labeled carbon monoxide capable of controlling the abundance ratio of a specific kind of the stable oxygen isotope to be an arbitrary value, the present invention provides a method for producing stable isotope labeled carbon monoxide including: a first mixing step in which carbon monoxide selectively containing at least one kind of stable isotope selected from the group consisting of 12C16O, 12C17O, 12C18O, 13C16O, 13C17O, and 13C18O, and water vapor selectively containing at least one kind of stable isotope selected form the group consisting of H216O, H217O and H218O are mixed to produce stable isotope labeled carbon dioxide: and a second mixing step in which the stable isotope labeled carbon dioxide produced in the first mixing step and hydrogen are mixed.