The report by the Dagens Nyheter was based on a study of criminal records of people who work at public schools in Sweden's 290 municipalities, TheLocal.se said.
One example the report cited involved a man in his 20s working at a primary school in western Sweden despite having been convicted of forcing a 14-year-old girl to repeatedly have sex with him.
Besides 97 people convicted of sex crimes, the newspaper found an additional 100 employees, including teachers, who are under suspicion for sex crimes but haven't faced trial yet.
The newspaper said many of the sex offenders were school employees when they committed crimes and were not covered by legislation passed a decade ago that requires criminal background checks for new hires.
A loophole in the law allows people who remain employed at the same school to hide their convictions from their employers, the report said.
The Ombudsman for Children in Sweden wants to see new legislation so that schools are informed when a teacher is convicted of a serious crime.