A reproducing/recording apparatus includes a first reproducing/recording mechanism (21) for reproducing data from and/or recording data onto a cartridge/disk combination (first disk) (1) or a bare disk (second disk) (2), the disk main body (1A) being contained in the cartridge (1B). The first reproducing/recording mechanism (21) has a traversing mechanism (50) disposed oppositely relative to the recording area of the first disk (1) or the second disk (2), a clamping mechanism (60) disposed oppositely relative to the traversing mechanism (50) with the first disk (1) or the second disk (2) interposed between them in order to clamp the first disk (1) and a keep member (64) adapted to bias the first disk (1) toward the side of the first disk tray at the time of clamping the first disk (1) by the clamping mechanism (60). The disk made to show a right attitude because the disk is pressed by the keep member (64) even when the first disk (1) is pushed up at an edge thereof by the sensor section arranged at the traversing mechanism (50).