A disk 100 has an electronic circuit 10 for executing predetermined signal process and/or an electronic function part having a function of generating, writing or preserving some electronic data and at least one electrical conductive part 20 electrically connected to the electronic circuits and/or electronic function part. The disk 100 is to be set on the turntable 210, clamped by the clamp and driven for rotation for reading or writing data. The clamp has an electrical conductive part formed on locality corresponding to the electrical conductive part 20 of the disk 100.