The report is based on interviews with 62 North Koreans who fled the country and provided detailed accounts of rape and sexual abuse.
The group said it revealed a culture of open, unaddressed abuse, particularly from men in positions of power.
"They consider us [sex] toys. We are at the mercy of men," Oh Jung-hee, a former trader in her 40s told the report's authors.
"Sometimes, out of nowhere, you cry at night and don't know why."
According to HRW some women said that sexual abuse had become so normalised that they did not think it was "unusual" - with some saying it had become accepted as part of everyday life.