The company, known for its Playstations and Xperia smartphones, will cut its total workforce in the southern town of Lund from 2,200 to 1,200 employees.
"We had a meeting with all of our employees where the CEO (Kazuo Hirai) presented the structural changes from April 1," Sony Mobile's chief executive in Sweden Bengt Arne Molin told reporters.
Sony's mobile division plans to shed by March 2016 a total of 2,100 jobs about 30 percent of its workforce to drag its results out of the red.
The mobile and tablet maker lost $1.2 billion (roughly Rs. 7,539 crores) in the fourth quarter of 2014 alone.
"It's very sad news for our members and for business," union the Swedish Association of Graduate Engineers said in a statement.
Sony, which acquired Swedish mobile maker Ericsson in 2012, relies on its Lund factory primarily for research and development, Molin said.
"Lund will play an important role in our future business especially within software, systems engineering and customer support," he added.
Last month Sony said it was selling its laptop business outright and hiving off its troubled television business into a wholly-owned subsidiary.