A coil substrate, comprising: a flexible substrate having a rectangular planar shape having two surfaces (F, S) and a first end on a first short side and a second end on an opposite short side with respect to the first end; a first coil (CFm) formed on a first surface of the flexible substrate such that the first coil (CFm) has a center space and a first wire surrounding the center space; and a second coil (CSm) formed on a second surface of the flexible substrate on an opposite side with respect to the first surface such that the second coil (CSm) has a center space and a second wire surrounding the center space and is positioned directly on the opposite side with respect to the first coil (CFm), characterized in that the first coil (CSm) is formed by the first wire, wherein the first wire includes a fifth wire, a sixth wire, and a seventh wire, wherein the fifth wire is placed straight against one end of the board, the sixth wire is arranged to face the fifth wire with a central space interposed therebetween and the seventh wire connects the fifth wire and the sixth wire and is curved, the second coil (CSm) is formed by the second wire, wherein the second wire includes the eighth wire, the ninth wire, and the tenth wire, wherein the eighth wire is arranged straight to one end of the board, the ninth wire is arranged to face the eighth wire across the center space and the tenth wire connects the eighth wire and the ninth wire and is curved, wherein a wire extending from the spiral inner end of the second coil (CSm) is a third wire, a wire that extends to the spiral outer end of the second coil (CSm) is a fourth wire, the second wire, the eighth wire, the ninth wire, and the tenth wire, are arranged in a spiral shape between the outer end and the inner end, wherein the first coil (CFm) is formed such that a number of turns in the first coil (CFm) is greater than a number of turns in the second coil (CSm) and the width of the first wire, the width of the fifth wire, the width of the sixth wire, and the width of the third wire that constitute the first coil are equal, and the width of the first wire forming the first coil (CFm) is substantially constant from the outer end to the inner end, and the width of the third wire and the width of the fourth wire constituting the second coil are not equal, and the width of the second wire forming the second coil (CSm) is not constant from the outer end to the inner end. a flexible substrate having a rectangular planar shape having two surfaces (F, S) and a first end on a first short side and a second end on an opposite short side with respect to the first end; a first coil (CFm) formed on a first surface of the flexible substrate such that the first coil (CFm) has a center space and a first wire surrounding the center space; and a second coil (CSm) formed on a second surface of the flexible substrate on an opposite side with respect to the first surface such that the second coil (CSm) has a center space and a second wire surrounding the center space and is positioned directly on the opposite side with respect to the first coil (CFm), characterized in that the first coil (CSm) is formed by the first wire, wherein the first wire includes a fifth wire, a sixth wire, and a seventh wire, wherein the fifth wire is placed straight against one end of the board, the sixth wire is arranged to face the fifth wire with a central space interposed therebetween and the seventh wire connects the fifth wire and the sixth wire and is curved, the second coil (CSm) is formed by the second wire, wherein the second wire includes the eighth wire, the ninth wire, and the tenth wire, wherein the eighth wire is arranged straight to one end of the board, the ninth wire is arranged to face the eighth wire across the center space and the tenth wire connects the eighth wire and the ninth wire and is curved, wherein a wire extending from the spiral inner end of the second coil (CSm) is a third wire, a wire that extends to the spiral outer end of the second coil (CSm) is a fourth wire, the second wire, the eighth wire, the ninth wire, and the tenth wire, are arranged in a spiral shape between the outer end and the inner end, wherein the first coil (CFm) is formed such that a number of turns in the first coil (CFm) is greater than a number of turns in the second coil (CSm) and the width of the first wire, the width of the fifth wire, the width of the sixth wire, and the width of the third wire that constitute the first coil are equal, and the width of the first wire forming the first coil (CFm) is substantially constant from the outer end to the inner end, and the width of the third wire and the width of the fourth wire constituting the second coil are not equal, and the width of the second wire forming the second coil (CSm) is not constant from the outer end to the inner end.