A 29-year-old woman who worked as a KAATSU (a type of body exercise that involves blood flow restriction) instructor visited our emergency room with a chief complaint of swelling and left upper limb pain. Chest computed tomography (CT) showed non-uniform contrast images corresponding to the site from the left axillary vein to the left subclavian vein; vascular ultrasonography of the upper limb revealed a thrombotic obstruction at the same site, leading to a diagnosis of Paget-Schroetter syndrome (PSS). We herein report our experience with a case of PSS derived from thoracic outlet syndrome (TOS), in a patient who was a KAATSU instructor.