Montoire sur le Loir is a very old fortified town, known under the name of Aureum Mons in medieval latin. During the wars between Henry II of England and Philip Augustus, Richard the Lionheart takes, in 1188, the Chateau de Montoire before heading on towards Lavardin.
Monteor or Montoire is promoted capital of the Bas-Vendômois under Jean V, who organizes the split of the land of Vendôme. Maison de Vendôme passes to the Bourbons, before returning to the Royal House in 1712.
During the French Revolution, the commune, then named Querhoent, was again named Montoire. It is also around this time, between 1790 and 1794, that is absorbed the neighbouring commune of Saint-Oustrille.