A signal processing circuit includes: multiple digital-signal processing units operating in parallel each including a selecting unit for selecting one of multiple systems of input picture signals, a double-speed converting unit for writing the data equivalent to one field of the picture signal selected by the selecting unit in field memory, and simultaneously reading the data equivalent to one field from the field memory twice at double speed, thereby converting the frequency of the picture signal into double speed, a reading unit for reading the picture signal converted into double speed by the double-speed converting unit and temporarily stored in line memory, and a correction processing unit for subjecting the picture signal read by the reading unit to predetermined correction processing; and a control unit for performing the selection control of the multiple systems of picture signals, and the read position control of a picture signal from the line memory.