The Plessis estate is mentioned as a seigneury as early as 1260.
In 1753, the medieval castle, having become too uncomfortable, was rebuilt and replaced with the one we see today, in the classical style.
In 1760, the blessing of the castle chapel took place; it was destroyed during the Revolution.
Among the most illustrious occupants of the estate, we can mention:
François Dollier de Casson (1636-1701), a cavalry captain and later a priest, who was sent on a mission to Quebec. He drew up part of the plans for the city of Montreal (the city owes its characteristic checkerboard structure to him, long before Philadelphia). In Montreal, a street, several buildings, and a retirement home now bear the name Casson.
Jacques-Olivier Urvoy de Saint-Bedan (1780-1858) was mayor of Casson, general councilor, member of parliament for Loire-Inférieure, and city councilor of Nantes. He was an important patron of the arts, notably responsible for the construction of the Sainte-Anne asylum (Hospices of the Little Sisters of the Poor), the church of Casson, the bell tower of the church of Sucé, the Sainte-Anne de Casson chapel, and more. His art collection is now largely on display at the Nantes Art Museum thanks to his generous donation.
The estate became the property of the Boux de Casson family. It then passed by inheritance to the Urvoy de Saint-Bedan family and then, through marriage, to the de Bouillé family, who still reside there.