This makes savers pay to keep money in storage - a move the bank hopes will force spending and boost the economy.
The bank has the task of keeping inflation at 2 percent. Currently Sweden has deflation, meaning it is far less profitable for investors to back employers who want to expand and hire more staff.
The bank does not rule out taking the interest rate further into the minus.
A rise in the inflation rate would make the bank likely to raise this main (repo) interest rate, but that is not expected before the second half of 2016, reports news agency TT.
There are fears Swedish banks may now start charging customers even more for having bank accounts.