Public executions had declined since 2000 amid international criticism but have been increasing, targeting officials accused of drug trafficking, embezzlement and other wrongdoing, the Good Friends aid agency said in a report on the North's human rights.
In October, the North executed the head of a factory in South Pyongan province for making international calls on 13 phones he installed in a factory basement, the aid group said. He was executed by a firing squad in a stadium before a crowd of 150,000 people.
Six people were also crushed to death and 34 others injured in an apparent stampede as they left after the execution, said the aid group.
Most North Koreans are banned from communicating with the outside world, part of the regime's authoritarian policies seeking to prevent any challenge to the iron-fisted rule of Kim Jong Il.
The North has carried out four other similar public executions by firing squad against regional officials and heads of factories in recent months, said the aid group.
"It is aimed at educating (North Koreans) to control society and prevent crimes," Good Friends head Venerable Pomnyun said in a press conference.
Good Friends, which did not say how it obtained the information, gave no exact figures of the public executions this year. Some of the group's previous reports of what was happening inside the North have later been confirmed.
The report came a week after a U.N. General Assembly committee adopted a draft resolution expressing "very serious concern" at reports of widespread human rights violations in North Korea , including public executions.
The resolution, co-sponsored by more than 50 countries including the United States and many other Western nations, was sent to the 192-member General Assembly for a final vote.
The North has condemned the draft, saying it was inaccurate and biased.
The communist country insists it does not violate human rights, but it has long been accused of imposing the death penalty for political reasons, holding thousands in prison camps, torturing border-crossers and severely restricting freedom of expression and religion.