It is an object of the present invention to provide a signal processing device which, even when a steep difference in DC level is included in a signal read from a disc such as a DVD-RAM format, cuts off the DC level and pulls the read signal into an appropriate A/D input level with an attempt to cost reduction. A steep difference in DC level between a data section and a CAPA section is absorbed by a first offset unit 1, and an asymmetry which occurs due to variations in the disc manufacturing stage is corrected by a second offset unit 2. Further, a control signal for operating the two offset units exclusively is generated by a controller 7, thereby to control the both offset units.