A posture-improving support garment according to an embodiment of the present invention is one comprising: a main body section 10 covering at least the upper body; and a beltlike straining section 20 having a straining force stronger than that of the main body section 10, wherein the straining section 20 extends right and left downward from at least any one of the seventh to ninth thoracic vertebrae, passes via lower portions of the right and left ribs, and joins at a center of the lower abdomen, and wherein at the center of the lower abdomen, a center line of the straining section 20 is located between the navel and the upper end of the pubis.