Undershirt

An undershirt worn in a state of being substantially in close contact with a surface of an upper body of a wearer, the undershirt comprising a main constituent portion made of stretchable materials that include a first-type material, a second-type material, and a third-type material,

• the first-type material having a straining force greater than a straining force of the second-type material, and
• the second-type material having a straining force greater than a straining force of the third-type material,
• wherein
• the first-type material is arranged in regions such that in each region the material covers at least a part of musculus triceps brachii, and terminates adjacent an upper end of the musculus triceps brachii, so as to be stretched when an elbow of the wearer is bent during a pitching motion,
• the third-type material is arranged in regions such that in each region the material covers at least a part of a lateral portion of musculus trapezius, at least a part of a superior portion of musculus latissimus dorsi, and at least a part of a medial portion of musculus deltoideus in a vicinity of scapula, and
• the second-type material is arranged in regions other than the regions where the first-type and third-type materials are arranged.