The transport ministry will start trial operations of full-body scanners from Thursday at Kansai Airport, with further trials later at the Narita and Haneda airports in the Tokyo area.
Full-body scanners use radio waves to reveal items concealed under passengers' clothing, and are being used to prevent hazardous materials from being brought onto airplanes.
The equipment is seen as a potent weapon against acts of terrorism.
Initial government policy was to split the costs necessary for security equipment at airports between the airline company in charge of security checks and airport administrators including the Land, Infrastructure, Transport and Tourism Ministry, relevant local governments and airport operating companies.
This changed, however, in response to the killing of Japanese nationals by the Islamic State of Iraq and the Levant (ISIL) militant group.
Ahead of the 2020 Tokyo Olympics and Paralympics, the ministry will cover all necessary costs to strengthen the security system at the main international airports managed by the ministry.
When a person enters a full-body scanner, their entire body is exposed to millimeter radio waves, and the machine picks up reflected waves to detect suspicious objects.
A full-body scanner can detect in seconds hazardous materials concealed under clothing, such as explosives that evade metal detectors or sharp tools that are not made from metal.
A monitor displaying a generic human form automatically indicates the results of the screening.
The strength of the radio waves used in the inspection ranges from about several hundredths to several ten-thousandths of those of cell phones. The ministry has said there is no effect on the human body.
Full-body scanners started to be introduced in the United States, Britain and other countries following a failed terrorism attempt in 2009 in which a man on a US airplane tried to detonate an explosive that a metal detector did not find.
The machines are now widely used mainly in Europe and the United States.
In Japan, test operations of full-body scanners were conducted at Narita Airport in 2010 with the aim of introducing the equipment for regular use.
However, some full-body scanners used in the test operations caused problems by clearly disclosing the body shape of the person being inspected.
The government's initial policy of splitting equipment costs between airline companies and airport administrators also hindered their widespread introduction, as full-body scanners cost several tens of millions of yen each.
Following the hostage crisis in which Japanese nationals were killed by ISIL, the government decided to strengthen security checks at airports.
For major international airports managed by the ministry, such as Haneda Airport, the ministry will shoulder all necessary costs to introduce full-body scanners, so the equipment will be installed in those airports.
Full-body scanners are expected to be installed within the next fiscal year at the three airports where the trial operations will be conducted, and the ministry plans to install the equipment in other major airports in the future.
Concerning airports managed by organisations other than the ministry, the ministry will instruct relevant organisations to install full-body scanners by having carriers, airport administrators and others bear the necessary costs.
Based on the lessons learned from the test operations at Narita Airport in 2010, the models to be used in the latest trial will not clearly disclose body shapes. Also, out of consideration for people's privacy, data obtained by the machine will be deleted after every inspection.
During the trial period, all travelers will be asked to go through the full-body scanners to study the extent of congestion when the equipment is used and the reactions of passengers who undergo the inspection.
By doing so, the ministry will examine problems concerning the practical use of full-body scanners.
Four models made in countries including the United States and Germany will be used in the trial operations. The ministry will ask airline companies to choose the models that are easy to use.