By studying spectrochemically the decomposition processes of carohemoglobin, oxyhemoglobin, methemoglobin, and carboxyemoglobin in the presence of 1-ascorbic acid and molecular oxygens the author obtained the following results. 1. In the case of carbohemoglobin besides tha already-known absorption peaks of 556 mμ and 430 mμ it shows another absoorption peak at 760 mμ, and its EmM is 1.4-2.0. 2. The absorption curve of the 670 mμ and 630 mμ substances at the time of deoxydation by sodium dithionite and causatic soda show the absorption peak at 618 mμ and 760 mμ. 3. The decomposition of caroxyhemoglobin takes similar decomposition processes as taken by oxyhemoglobin and methemoglobin, producing the 670 mμ and 630 mμ substances. In other words, it seems that caroxyhemoglobin is reduced to hemoglobin by liberating carbon monoxide and then it enters into decomposition processes, and its decomposition is extremely slow as compared with that of oxyhemoglobin and methemoglobin. 4. CO-choleglobin is not an intermediate product of carboxyhemoglobin decomposition but it is produced at the time when choleglobin comes in contact with carbon monoxide. 5. CO-choleglobin is split into carbon monoxide and choleglobin in the presence of 1-ascorbic acid and molecular oxygens.