A medical signal processing device 6 receives a picture signal imaged by a medical observation device 2 and processes the picture signal. The medical signal processing device 6 includes: a signal input unit 61 that receives the picture signal; a first signal converting unit 62 that converts the picture signal received by the signal input unit 61 from an RGB signal into a luminance signal and a color difference signal by performing a matrix calculating process; an identification information appending unit 63 that appends color gamut identification information related to a color gamut of the picture signal and corresponding to the matrix calculating process, to the picture signal resulting from the conversion; and a signal output unit 64 that outputs the picture signal to which the color gamut identification information has been appended, to either a medical display device 4 or a medical recording device provided externally.