A screw fastening process can be performed by reliably positioning a screw in a screw hole while suppressing a decrease in the degree of freedom of movement of a screw fastening device. Provided is a screw guide device that guides a screw to a screw hole. The screw is fastened by a screw fastening device to the screw hole formed in a workpiece to be fastened to be fastened. The screw guide device includes a guide device body provided at a support that supports the workpiece to be fastened, and also includes a guide member that is provided in the guide device body and that is openable and closable in a radial direction orthogonal to a central axis of a shaft section of the screw. The guide member forms a screw insert through which the shaft section is inserted when the guide member is in a closed state.