A mating guide part formed with a mating recess part that has a substantially rectangular shaped in a plan view with a first high frequency connection unit mounted therein is included, the first high frequency connection unit includes a first high frequency terminal and a square tube shaped first high frequency shield with a substantially rectangular cross section extending in the mating direction enclosing around the first high frequency terminal, the second connector includes a counterpart mating guide part that has a substantially rectangular shape in a plan view with a second high frequency connection unit mounted therein, and the second high frequency connection unit includes a second high frequency terminal and a square tube shaped second high frequency shield with a substantially rectangular cross section that extends in the mating direction enclosing around the second high frequency terminal.