Sandvik said the deal includes exploration rigs, consumables and production stock as well as some trademarks and patents.
The Exploration business is currently booked under the Sandvik Mining and Rock Technology operations.
Drillman supports and equips customers in the geotechnical, mineral exploration, horizontal, directional and upstream gas drilling sectors.
Sandvik president and chief executive Stefan Widing said the deal is in line with "our focus to further improve the efficiency and profitability of our company".
Harry Mostert, chief executive of M Group, added: "The acquisition forms part of our long-term strategy to expand our international footprint and we are eager to introduce our passion for the mining and exploration business into the global market."
The deal is expected to close during the fourth quarter this year.
In 2019, the Exploration business had revenues of about SEK450 million (US$51 million) and a margin slightly dilutive to Sandvik Mining and Rock Technology.