A configuration of the ground finger provided in the pluggable transceiver is disclosed, which makes the gap between the transceivers ideally small even when a plural transceiver is set in side-by-side arrangement within a single cage. The transceiver has side fingers in both side walls thereof, whose levels are different from each other such that, when these transceivers are set in side-by-side arrangement within the single cage, they come in contact with sides of the next transceiver so as not to interfere the contact.