SNC Lavalin has issued layoff notices to 405 people, most of them in its mining division.
186 people in Montreal are being laid off, while 195 losses are posted in Ontario, and 24 in Saskatoon.
The company is also closing an office in Sudbury, but employees based out of that office will work directly with clients.
Overall 70 percent of the losses are in mining and metallurgy.
SNC Lavalin's mining division has been struggling for several years as a result of changes in the global economy.
Louis Antoine Paquin of SNC Lavalin said the company is looking to alter its focus in order to grow its operational margin to 7 percent next year. This year it's been averaging 4.3 percent.
The company has been in a long restructuring phase that included 4,000 layoffs from late 2014 to early 2016, but has hired 2,000 people this year.