Hærbygaard is a manor house and estate located on Tuse Næs, Holbæk Municipality, some 80 kilometres west of Copenhagen, Denmark.

The current main building was constructed for Melchior Grevenkop-Castenskiold in 1861-62 and later expanded with a new north wing by Gotfred Tvede in 1900-1901.

[2] Mogens Godskesen kept the estate after it was confiscated by the Crown after the Reformation in 1536 and he was also granted Dragsholm.

[3] In 1692, Christian V granted the estate to Admiral Henrik Span who was at the same time raised to the peerage.

Jacoba von Holten, the widow of Johan Lorentz Castenschiold, acquired the estate in 1748.

She ceded the estate to their second eldest son Jørgen Frederik von Castenschiold in 1760.

Jørgen Frederik von Castenschiold's son Casper inherited the estate in 1813.

His son Joachim Melchior Grevenkop-Castenschiold, who had inherited the estate in 1854, constructed a new main building in around 1861.

The building was in the 20th century from 1935 for a while owned by a family trust and used as a summer camp for children from Copenhagen and a home for working class widows.