A stringed musical instrument including a body in which a cutaway is formed, wherein the body includes a back board on which at least one brace (14_1-14_4) is provided so as to extend in a width direction of the back board, a longitudinal direction of each of the at least one brace coinciding with the width direction of the back board, wherein a first brace (14_1), which is the closest to the cutaway among the at least one brace (14_1-14_4), has a dimension in the width direction of the back board smaller than a width of the back board at a position of the back board at which the first brace is fixed, the first brace being fixed to the back board such that a distance between a first end (14_1a) of the first brace (14_1) and a first edge portion of the back board is larger than a distance between a second end (14_1b) of the first brace (14_1) and a second edge portion of the back board, two edge portions on an outer periphery of the back board in the width direction at the position of the back board at which the first brace (14_1) is fixed including the first edge portion and the second edge portion that is farther from the cutaway than the first edge portion, the first end (14_1a) of the first brace (14_1) and the second end (14_1b) of the first brace (14_1) being opposite ends of the first brace (14_1), the first end (14_la) of the first brace (14_1) being nearer to the cutaway than the second end (14_lb) of the first brace (14_1) characterized in that the first end (14_1a) of the brace (14_1) is fixed to the back board at a position that is downwardly distant, by a predetermined distance, from a position at which the cutaway is the deepest, the predetermined distance being not smaller than 1 cm, and the first brace (14_1) has a thickness in a direction perpendicular to the back board smaller at its opposite end portions in the width direction than at its central portion in the width direction, and the first brace (14_1) has a shape that is symmetric in the width direction of the back board. wherein the body includes a back board on which at least one brace (14_1-14_4) is provided so as to extend in a width direction of the back board, a longitudinal direction of each of the at least one brace coinciding with the width direction of the back board, wherein a first brace (14_1), which is the closest to the cutaway among the at least one brace (14_1-14_4), has a dimension in the width direction of the back board smaller than a width of the back board at a position of the back board at which the first brace is fixed, the first brace being fixed to the back board such that a distance between a first end (14_1a) of the first brace (14_1) and a first edge portion of the back board is larger than a distance between a second end (14_1b) of the first brace (14_1) and a second edge portion of the back board, two edge portions on an outer periphery of the back board in the width direction at the position of the back board at which the first brace (14_1) is fixed including the first edge portion and the second edge portion that is farther from the cutaway than the first edge portion, the first end (14_1a) of the first brace (14_1) and the second end (14_1b) of the first brace (14_1) being opposite ends of the first brace (14_1), the first end (14_la) of the first brace (14_1) being nearer to the cutaway than the second end (14_lb) of the first brace (14_1) characterized in that the first end (14_1a) of the brace (14_1) is fixed to the back board at a position that is downwardly distant, by a predetermined distance, from a position at which the cutaway is the deepest, the predetermined distance being not smaller than 1 cm, and the first brace (14_1) has a thickness in a direction perpendicular to the back board smaller at its opposite end portions in the width direction than at its central portion in the width direction, and the first brace (14_1) has a shape that is symmetric in the width direction of the back board.