Sint Martinus (English: Saint Martin) is a tower mill in Didam, Gelderland, Netherlands which was built in 1855 and has been restored to working order.

In 1854, Theodorus Kempers was given permission to build a corn and pearl barley mill at Didam.

In 1942, the sails were fitted with streamlined leading edges on the Van Bussel system.

The work was carried out by millwright Groot Wesseldijk of Laren, North Holland.

This drives a pair of 1.50 metres (4 ft 11 in) diameter French Burr millstones via a lantern pinion stone nut with 27 staves.