A magnetic recorder or reproducer in an electronic camera system wherein a subject is pure-electronically still-photographed and recorded on a rotating magnetic disc, and the reproducing of an image is carried out by a television system or a printer.In this rotary magnetic recording-reproducing apparatus, the addressing of tracks is performed under two modes including absolute addresses and relative addresses, so that the most proper mode can be used in accordance with the purpose of use of the track addresses. Particularly, the adverse influence of a shift in the addressing due to a dropout can be eliminated and a shift in the numbering when the track number is displayed can be also eliminated.