A signal processing device that is connected to a medical observation device that performs an examination inside a subject and outputs an image signal including a plurality of frames output sequentially according to a result of the examination, and that outputs a video signal for display, the signal processing device comprising: a first internal module configured to execute hardware processing; and a second internal module (62,63) configured to execute software processing, wherein the first internal module configured to output the image signal input from the medical observation device, division position information indicating division positions at which a frame of the image signal is divided by a predetermined amount of data into a plurality of portions, and a timing signal indicating processing timing of the software processing to be performed sequentially on each of the plurality of portions, to the second internal module, and to generate, based on the image signal that has been subjected to the software processing and input from the second internal module, the video signal for display, the predetermined amount of data at which the frame of the image signal is divided into the plurality of portions being set based on a type of camera connected to the medical observation device, and the second internal module (62,63) is configured to sequentially execute, based on the timing signal and the division position information, image processing on each portion in the plurality of portions in the image signal per the predetermined amount of data, through the software processing, and sequentially output each portion in the plurality of portions of each frame in the image signal per the predetermined amount of data that has been subjected to the image processing, to the first internal module. a first internal module configured to execute hardware processing; and a second internal module (62,63) configured to execute software processing, wherein the first internal module configured to output the image signal input from the medical observation device, division position information indicating division positions at which a frame of the image signal is divided by a predetermined amount of data into a plurality of portions, and a timing signal indicating processing timing of the software processing to be performed sequentially on each of the plurality of portions, to the second internal module, and to generate, based on the image signal that has been subjected to the software processing and input from the second internal module, the video signal for display, the predetermined amount of data at which the frame of the image signal is divided into the plurality of portions being set based on a type of camera connected to the medical observation device, and the second internal module (62,63) is configured to sequentially execute, based on the timing signal and the division position information, image processing on each portion in the plurality of portions in the image signal per the predetermined amount of data, through the software processing, and sequentially output each portion in the plurality of portions of each frame in the image signal per the predetermined amount of data that has been subjected to the image processing, to the first internal module.