A recording and/or reproducing apparatus includes an optical system arranged to form an optical image, a photo-electric conversion part arranged to convert the optical imaged into an electrical signal, an A/D conversion circuit arranged to convert the electrical signal and/or an audio signal into a digital signal, a connector arranged to permit mounting and demounting a recording medium on which the digital signal obtained from the A/D conversion circuit is to be recorded, and a signal processing part for processing and converting the digital signal. The signal processing part is arranged to be mountable and demountable on and from the apparatus.