To provide a modular jack having reduced mismatch of impedances.

This modular jack is equipped with plural terminal pieces 51-58, to which the conductors of a jack side cable provided with plural pairs of the conductors are connected respectively, plural contacts 31-38 arranged adjacently in a hosing 1, so as to be brought into elastic contact with the contacts of a modular plug inserted in the housing 1 through a plug inserting opening provided on the front surface of the housing 1, and a printed circuit board 4 on which plural wiring patterns to electrically connect the terminal pieces 51-58 to the corresponding contacts 31-38 respectively are formed. First and second flat conductor parts 7, 8 are made to protrude respectively from the end rims of the contacts 33-36 connected electrically respectively to the conductors forming the pair, the first and second conductor parts 7, 8 are counterposed with a prescribed gap interposed, and the impedance between the contact 33-36 is reduced, because the space between the first and second conductor parts 7, 8 is coupled electrostatically.