"In reality, however, military service is not as glorious as it appears from the outside," the human rights group said in a report based on testimonies of North Korean female defectors.
"Violence against women and sexual abuse are especially notorious within construction units," it said.
"In the military, all men go after pretty girls," Kim Young-Ok, who served in the military from 1992 to 2003 before fleeing the North in 2008, said in her testimony.
"When young female soldiers get raped, they cannot report to anywhere," she said. If acts of sexual violence against them are publicized, women are stripped of opportunities to get married and get a promotion, Kim said.
"Victims of sexual or physical violence are forced to try to hide what happened to them because of the general perception that any sexual violence a woman face was promoted by her," the defector said.
Sexual violence is so rampant especially in military construction units that any girl sent to the unit is considered to be "a piece of trash."
"No one believes that women who have been in military construction unit are virgins," said Park Kum-Bong who defected to the South in 2005 after serving in a military construction unit in the North.
"Just as violence against women is widely tolerated within the domestic sphere, various acts and forms of physical, sexual and psychological violence are pervasive with the North Korean society," the human rights group said in the report.