To provide a method by which a protective sleeve attachable to a component having an irregular shape or an already attached long component can be produced in excellent productivity.

The method for producing the protective sleeve having an opening part continuing in the longitudinal direction is obtained by braiding a fiber yarn by a braider to provide a braided sleeve, cutting up the braided sleeve in the longitudinal direction to afford the opening part, forming the diameter-reduced shape by overlapping the opening parts and holding the shape having the reduced diameter by subjecting the product to heat treatment. The method for producing the protective sleeve includes a step for coating a sizing agent on the braided sleeve and heating and curing the sizing agent. Preferably, the overlapped proportion represented by the proportion of the length of the overlapped part based on the circumferential length of the cross-section of the protective sleeve is not less than 10% and not more than 50% in the method for producing the protective sleeve.