An information recording and retrieval system, such as an optical system, for recording and reading signals, such as video signals and audio signals, on a recording medium provides improvement in the control of a moving part, such as an objective lens. In a first embodiment, reading of code signals is detected to disable the control of the moving part by the recorded code signals, recorded as discontinuities in a recording track, and to enable control by information signals, recorded as changes in reflectivity in the track, held by a holding circuit so that only recorded information signals operate the control to avoid control distrubances caused by differences in the recorded code and information signals. In another embodiment peak detecting circuits detect the minimum values of split detection signals for controlling the moving part; use of these minimum values for control avoids the control disturbances from the differences in signal reading during recording and reading modes.