The first trace of humans around Hamra comes from the Older Iron Age. It is then that the Ancient castle that lies situated on a hill by the shore of Lake Tullinge was built. Several grave fields from the younger Iron Age lie around Hamra. There is also a Rune Stone from the Viking Age that is standing at Hamra gård. In the end of the 13th century the name Hamra was mentioned for the first time in written sources. It is then owned by a relative of the holy Saint Birgitta Some centuries later, in the end of the 17th century, Hamra Manor was built. It is situated on a hill a couple of hundred meters away from the village. In 1765 the building was torn down and a new building was built. That building is still very well kept. Today it is owned by DeLaval and is sometimes used for meetings and conferences. In the year 1894 AB Separator (what is now known as DeLaval) bought Hamra with the intention of trying out a new invention that increased the quality of the milk. The invention was called the Milk Separator and its purpose was to produce tubercle free milk. Tubercolusis is a dangerous illness and with the help of DeLaval, the disease was no longer found in milk. The invention became a success and its inventor, Gustav DeLaval, became rich and popular because of it. Hamra gård is still working on improved methods of milking and running a farm.