A board-to-board connector (10; 20) for electrically connecting a first printed circuit board (p1; p3) to a second printed circuit board, the board-to-board connector comprising a first connector (1; 3) and a second connector, the first connector (1; 3) being mountable on the first printed circuit board (p1; p3), the second connector being mountable on the second printed circuit board, wherein the first connector (1; 3) comprises: a rectangular parallelepiped first housing (11; 31) which includes a concave portion (11c; 31c) having one opened surface and adapted to fit to the second connector and a first contact accommodation chamber (11r; 31r) having the other opened surface; and one or more floating first contacts (12; 32) of which one end portion is fixable to the first printed circuit board (p1; p3), the other end portion is fixed to the first housing (11; 31), and an intermediate portion is accommodated in the first contact accommodation chamber (11r; 31r) and in which the first housing (11; 31) is movably supported with respect to the first printed circuit board (p1; p3), wherein the second connector comprises a rectangular parallelepiped second housing which has an insertion hole opened to one surface thereof so that the first contact (12; 32) is insertable into the insertion hole, characterized in that the first contact (12; 32) comprises: a winding portion (122; 124; 125; 126) which includes a band-shaped metal plate, is wound inward by at least one revolution from a starting end portion to a terminal end portion along a first surface and a second surface at a side in which a distance between facing surfaces of the metal plate is long so that the terminal end portion reaches a center portion, and is formed at the intermediate portion; a lead terminal which forms the one end portion and protrudes in a direction perpendicular to the first surface at the starting end portion of the winding portion; and a contact terminal which forms the other end portion, protrudes in a direction perpendicular to the second surface at the terminal end portion of the winding portion, and is press-inserted into the first housing (11; 31) while protruding from a bottom surface of the concave portion (11c; 31c). a rectangular parallelepiped first housing (11; 31) which includes a concave portion (11c; 31c) having one opened surface and adapted to fit to the second connector and a first contact accommodation chamber (11r; 31r) having the other opened surface; and one or more floating first contacts (12; 32) of which one end portion is fixable to the first printed circuit board (p1; p3), the other end portion is fixed to the first housing (11; 31), and an intermediate portion is accommodated in the first contact accommodation chamber (11r; 31r) and in which the first housing (11; 31) is movably supported with respect to the first printed circuit board (p1; p3), a rectangular parallelepiped second housing which has an insertion hole opened to one surface thereof so that the first contact (12; 32) is insertable into the insertion hole, characterized in that the first contact (12; 32) comprises: a winding portion (122; 124; 125; 126) which includes a band-shaped metal plate, is wound inward by at least one revolution from a starting end portion to a terminal end portion along a first surface and a second surface at a side in which a distance between facing surfaces of the metal plate is long so that the terminal end portion reaches a center portion, and is formed at the intermediate portion; a lead terminal which forms the one end portion and protrudes in a direction perpendicular to the first surface at the starting end portion of the winding portion; and a contact terminal which forms the other end portion, protrudes in a direction perpendicular to the second surface at the terminal end portion of the winding portion, and is press-inserted into the first housing (11; 31) while protruding from a bottom surface of the concave portion (11c; 31c).