PROBLEM TO BE SOLVED: To provide a medical observation device and a medical observation system capable of acquiring a focal length according to an operating environment temperature. SOLUTION: An optical system composed of one or a plurality of lenses, an image pickup element that captures an image formed by the optical system, a temperature sensor that detects the ambient temperature of the optical system, and a detection result of the temperature sensor. A second focal length corrected for the first focal length based on the temperature information generator that generates the temperature information, the temperature information, and the first focal length calculated based on the position of the lens. It is provided with a focal length calculation unit for calculating. [Selection diagram] Fig. 2【課題】使用環境温度に応じた焦点距離を取得することができる医療用観察装置及び医療用観察システムを提供すること。【解決手段】一つ又は複数のレンズからなる光学系と、光学系が結像した像を撮像する撮像素子と、光学系の環境温度を検出する温度センサと、温度センサの検出結果に基づいて温度情報を生成する温度情報生成部と、温度情報と、レンズの位置をもとに算出される第１の焦点距離とに基づいて、該第１の焦点距離を補正した第２の焦点距離を算出する焦点距離算出部と、を備える。【選択図】図２
