A signal transmission cable (100, 2100) comprising: a total of seven units (110, 120, 130, 140, 2110, 2120, 2130; 210, 220, 230, 2210, 2220, 2230, 2240) comprising first coated conductor units (110, 120, 130, 140, 2110, 2120, 2130), each of which is formed by a first conductor (111, 121, 131, 141, 2111, 2121, 2131), and a dielectric (113, 123, 133, 143, 2113, 2123, 2133) formed on an outer periphery of the first conductor (111, 121, 131, 141, 2111, 2121, 2131), and a plurality of second conductor units (210, 220, 230, 2210, 2220, 2230, 2240), each of which has the same outer diameter as the first coated conductor unit (110, 120, 130,140,2110,2120,2130)and is disposed adjacent to the dielectrics (113, 123, 133, 143, 2113, 2123, 2133) of the first coated conductor units (110, 120, 130, 140, 2110, 2120, 2130), wherein one of the first coated conductor units of the total of seven units (110, 120, 130, 140, 2110, 2120, 2130; 210, 220, 230, 2210, 2220, 2230, 2240) is disposed at a center of the signal transmission cable (100, 2100), wherein the remaining six of first coated conductor units (120, 130, 140, 2110, 2120, 2130) and second conductor units (210, 220, 230, 2220, 2230, 2240) of the total of seven units (110, 120, 130, 140, 2110, 2120, 2130; 210, 220, 230, 2210, 2220, 2230, 2240) are alternately disposed around the one unit disposed at the center of the signal transmission cable (100, 2100) so as to be adjacent to each other, wherein a signal line is formed by one of the first coated conductor units (110, 120, 130, 140, 2110, 2120, 2130) and all the second conductor units (210, 220, 230, 2220, 2230, 2240) adjacent thereto, and wherein each first conductor unit (110, 120, 130, 140, 2110, 2120, 2130) is coated with a thickness so that the characteristic impedance of each signal line of the signal transmission cable becomes the same predetermined impedance. a total of seven units (110, 120, 130, 140, 2110, 2120, 2130; 210, 220, 230, 2210, 2220, 2230, 2240) comprising first coated conductor units (110, 120, 130, 140, 2110, 2120, 2130), each of which is formed by a first conductor (111, 121, 131, 141, 2111, 2121, 2131), and a dielectric (113, 123, 133, 143, 2113, 2123, 2133) formed on an outer periphery of the first conductor (111, 121, 131, 141, 2111, 2121, 2131), and a plurality of second conductor units (210, 220, 230, 2210, 2220, 2230, 2240), each of which has the same outer diameter as the first coated conductor unit (110, 120, 130,140,2110,2120,2130)and is disposed adjacent to the dielectrics (113, 123, 133, 143, 2113, 2123, 2133) of the first coated conductor units (110, 120, 130, 140, 2110, 2120, 2130), first coated conductor units (110, 120, 130, 140, 2110, 2120, 2130), each of which is formed by a first conductor (111, 121, 131, 141, 2111, 2121, 2131), and a dielectric (113, 123, 133, 143, 2113, 2123, 2133) formed on an outer periphery of the first conductor (111, 121, 131, 141, 2111, 2121, 2131), and a first conductor (111, 121, 131, 141, 2111, 2121, 2131), and a dielectric (113, 123, 133, 143, 2113, 2123, 2133) formed on an outer periphery of the first conductor (111, 121, 131, 141, 2111, 2121, 2131), and a plurality of second conductor units (210, 220, 230, 2210, 2220, 2230, 2240), each of which has the same outer diameter as the first coated conductor unit (110, 120, 130,140,2110,2120,2130)and is disposed adjacent to the dielectrics (113, 123, 133, 143, 2113, 2123, 2133) of the first coated conductor units (110, 120, 130, 140, 2110, 2120, 2130), has the same outer diameter as the first coated conductor unit (110, 120, 130,140,2110,2120,2130)and is disposed adjacent to the dielectrics (113, 123, 133, 143, 2113, 2123, 2133) of the first coated conductor units (110, 120, 130, 140, 2110, 2120, 2130), wherein one of the first coated conductor units of the total of seven units (110, 120, 130, 140, 2110, 2120, 2130; 210, 220, 230, 2210, 2220, 2230, 2240) is disposed at a center of the signal transmission cable (100, 2100), wherein the remaining six of first coated conductor units (120, 130, 140, 2110, 2120, 2130) and second conductor units (210, 220, 230, 2220, 2230, 2240) of the total of seven units (110, 120, 130, 140, 2110, 2120, 2130; 210, 220, 230, 2210, 2220, 2230, 2240) are alternately disposed around the one unit disposed at the center of the signal transmission cable (100, 2100) so as to be adjacent to each other, wherein a signal line is formed by one of the first coated conductor units (110, 120, 130, 140, 2110, 2120, 2130) and all the second conductor units (210, 220, 230, 2220, 2230, 2240) adjacent thereto, and wherein each first conductor unit (110, 120, 130, 140, 2110, 2120, 2130) is coated with a thickness so that the characteristic impedance of each signal line of the signal transmission cable becomes the same predetermined impedance.