A South Korean NGO says it has identified 318 sites in North Korea that have been used by the government to carry out public executions.
The Transitional Justice Working Group interviewed 610 North Korean defectors over four years for its report.
It documented decades of killings, for offences ranging from stealing a cow to watching South Korean TV.
Public executions took place near rivers, fields, markets, schools, and sports grounds, the rights group said.
The report alleges that family members of those sentenced to death, including children, were sometimes forced to watch the event. The bodies and burial locations of those killed were rarely given to their relatives.
The youngest person to witness a public killing was seven years old, according to testimony.
Some public executions also take place inside detention facilities such as prisons and labour camps - where people convicted of political crimes are forced into physical work such as mining and logging.
One defector held in a labour camp in the early 2000s described how 80 inmates were made to watch the killing of three women charged with trying to escape to China.
They said a Ministry of People's Security officer told the crowd: "This could happen to you."
The report said executions are "a core method of inciting fear and deterring citizens from engaging in activities deemed undesirable by the regime".