A connector for transmitting signals using electrostatic coupling, comprises an inner first conductor portion and an outer first conductor portion respectively connected to two signal lines, an inner electrode portion having a facing area larger than the cross-sectional area of the inner first conductor portion in the direction perpendicular to the direction of the common axis, an outer electrode portion outside it, an inner second conductor portion for electrically connecting between the inner first conductor portion and the inner electrode portion, and an outer second conductor portion outside it, wherein the ratio of outer diameter of the inner second conductor portion to inner diameter of the outer second conductor portion is set to provide substantially fixed characteristic impedance at every position along the direction of the common axis.