An operation support device having a surgical instrument unit and a surgical instrument unit support section, includes: an intermediate member connected to the surgical instrument support section and configured to hold the surgical instrument unit； a shielding member having a hole portion engaged with the intermediate member； and a driving force supply unit installed at the surgical instrument support section. A first space and a second space are formed by an assembly constituted by the shielding member and the intermediate member engaged with the hole portion as a boundary. The intermediate member is connected to the surgical instrument support section at a side of the first space, and holds the surgical instrument unit at a side of the second space. The driving force supply unit and the surgical instrument support section are disposed in the first space.
