A surface treatment processing method of shot peening to improve fatigue strength of parts subjected to repeated load, the method comprising: a first inspection step of nondestructively inspecting a surface side state of a treatment target to be subjected to shot processing of shooting shot media at the treatment target by measuring a residual stress on a surface side of the treatment target and magnetically evaluating the surface side of the treatment target by an eddy current and evaluating that the treatment target is not failed when an inspection result of the magnetic evaluation is not out of a predetermined allowable range and an inspection result of the residual stress measurement is within a predetermined allowable range; a condition setting step of setting a shot processing condition in response to the inspection result of the first inspection step for the treatment target evaluated as not failed in the first inspection step after the first inspection step by correcting a reference value of the shot processing condition based on the inspection result of the residual stress being out of a predetermined normal stress range; a shot processing step of performing shot processing of shooting shot media at the treatment target evaluated as not failed in the first inspection step in the shot processing condition set in the condition setting step after the condition setting step; and a second inspection step of nondestructively inspecting a surface side state of the treatment target after the shot processing step by measuring a residual stress on a surface side of the treatment target and magnetically evaluating the surface side of the treatment target by an eddy current, wherein in the second inspection step, it is evaluated that the treatment target is passed when an inspection result of the second inspection step is within the predetermined normal range, and the surface treatment processing method further comprises a reference value resetting step of resetting the reference value of the shot processing condition to suppress a ratio in which the inspection result of the second inspection step is out of the predetermined normal range based on a tendency of a temporal change in the inspection result of the second inspection step. a first inspection step of nondestructively inspecting a surface side state of a treatment target to be subjected to shot processing of shooting shot media at the treatment target by measuring a residual stress on a surface side of the treatment target and magnetically evaluating the surface side of the treatment target by an eddy current and evaluating that the treatment target is not failed when an inspection result of the magnetic evaluation is not out of a predetermined allowable range and an inspection result of the residual stress measurement is within a predetermined allowable range; a condition setting step of setting a shot processing condition in response to the inspection result of the first inspection step for the treatment target evaluated as not failed in the first inspection step after the first inspection step by correcting a reference value of the shot processing condition based on the inspection result of the residual stress being out of a predetermined normal stress range; a shot processing step of performing shot processing of shooting shot media at the treatment target evaluated as not failed in the first inspection step in the shot processing condition set in the condition setting step after the condition setting step; and a second inspection step of nondestructively inspecting a surface side state of the treatment target after the shot processing step by measuring a residual stress on a surface side of the treatment target and magnetically evaluating the surface side of the treatment target by an eddy current, wherein in the second inspection step, it is evaluated that the treatment target is passed when an inspection result of the second inspection step is within the predetermined normal range, and the surface treatment processing method further comprises a reference value resetting step of resetting the reference value of the shot processing condition to suppress a ratio in which the inspection result of the second inspection step is out of the predetermined normal range based on a tendency of a temporal change in the inspection result of the second inspection step.