A Vietnam Airlines flight from Japan to Vietnam was delayed by two hours and 20 minutes on Monday after a male Vietnamese passenger opened the emergency exit door without permission from the crew.
The incident happened at Narita International Airport while other passengers from Tokyo to Da Nang were boarding the plane.
The passengers were asked to return to the waiting area so the crew could deal with technical problems.
Vietnam Airlines issued compensation in line with regulations and transferred passengers who were making connections onto other flights.
Airline representatives at Narita Airport have reported the case to local authorities.
The passenger will be fined for violating aviation safety regulations.
Vietnam's aviation industry has been booming in recent years. The country served more than 94 million air passengers in 2017, up 16 percent from a year ago, including 13 million foreigners.