The construction industry currently faces two major issues. One is the steady retirement of older workers, and the other is the inability to recruit a sufficient number of young workers. One of the reasons behind these problems is the physical demands of construction work. If we could lessen these physical demands, we should be able to resolve these issues to a degree. In this study, we focused our attention on the clothing worn by construction workers. We propose the sewing of elastic materials into workwear, such that it causes tension in the direction in which the worker’s muscles contract. This tension will aid the movement of the construction worker. We obtained electromyogram measurements during actual construction work to determine the degree of physical fatigue and evaluate the degree of assistance provided by the workwear. We used three different types of workwear in three experiments: an X-1 type to investigate the reinforcement layout, an X-2 type in a wall-painting experiment, and a T-type in a floor-painting experiment. Based on the results, we were able to confirm that the assistive function of the workwear assisted the motion of the deltoid muscles in the reinforcement-layout and wall-painting experiments.