To provide an on-vehicle device capable of connecting a plurality of portable reproduction devices having different positions of communication interfaces.

The on-vehicle monitor device has turnable arm parts 22 and 30 in a vicinity of insertion ports 18 and 20 at both ends of a hole 16 penetrating a body 10, and connectors 26 and 28 are mounted on the arm parts 22 and 30. A portable reproduction device to be inserted from the insertion port 18 is connected to the connector 26 of the arm part 22, and a portable reproduction device to be inserted from the insertion port 20 is connected to a connector 34 of the arm part 30 provided in a vicinity of the insertion port 18.