A method of producing a blood glucose spike inhibitor is a preparation step for preparing a culture medium containing a bacterium capable of accumulating a poly (R) - 3-hydroxybutyric acid and a recovery step for recovering residues containing granules of poly (R) - 3-hydroxybutyric acid by solid-liquid separation of the culture medium and remaining It has a process for producing poly (R) - 3-hydroxybutyric acid powder by drying the wax.
