[Object] To control the focal position of an optical system with a more favorable aspect, in accordance with the band targeted for observation.[Solution] A medical observation device includes: a computation section that applies, to an imaging signal corresponding to each of a plurality of different spectral components based on a light receiving result regarding observation target light from a subject in vivo from an image sensor, weights of the plurality of spectral components corresponding to a band targeted for observation from among bands in the observation target light, and computes an evaluation value indicating a degree of being in-focus on a basis of the imaging signal to which the weights are applied； and a control section that controls, on a basis of the evaluation value, a position of at least one optical member in an optical system that forms an image of the observation target light from the subject onto the image sensor, and thereby controls a focal position of the optical system.
