The present invention relates to a disk recording and/or reproducing apparatus in which a disk-like recording medium such as an optical disk is transported between a disk loading portion provided for recording and/or reproducing information and a disk unloading portion for inserting and ejecting the disk-like recording medium. The disk recording and/or reproducing apparatus includes a pair of transport members for holding a disk-like recording medium in its diametrical direction, a drive means for driving a first transport member of the pair of transport members and giving rotation force to rotate and move the disk-like recording medium held between the pair of transport members and a space adjusting mechanism capable of adjusting a space by making the pair of transport members become close to or away from each other in response to the size of the disk-like recording medium. The disk-like recording medium can reliably be held in the diametrical direction by adjusting a space between the pair of transport members with the space adjusting mechanism in response to the size of the disk-like recording medium and the disk-like recording medium can be rotated, moved and transported by rotation force applied thereto. Therefore, when the disk is transported, the signal recording surface can be free from being touched, the signal recording surface can be prevented from being pressed by foreign material and the signal recording surface can be prevented from being scratched by the foreign material. Thus, an information signal can reliably be read and written.