PURPOSE: To enable filtering with an improved S/N ratio by improving resistance to noises with respect to a PPM binary signal read out of a recording medium.

CONSTITUTION: A film F having a magnetic track F2 formed thereon is sent along the length thereof by a motor 120 while a magnetic data as PPM binary signal is read out of the magnetic track F2. The PPM binary signal read out is inputted into a band-pass filter 3 via an amplifier 2. A low-pass cut-off frequency fCLK1 of the band-pass filter 3 is set to fCLK1=BD (MIN) × vf (MIN) and a high-pass cut-off frequency fCLK2 to fCLK2=BD (MAX) × vf (MAXI. The BD (MIN) is the minimum value of a data recording density (bit/mm) to a recording medium, the BD (MAX) is the maximum value of the data recording density (bit/mm) to the recording medium, the vf (MIN) the maximum value of a relative reading speed (mm/sec) and the vf (MAX) is the maximum value of the relative reading speed (mm/sec).