However, the country still has a long way to go to reach its Paris Agreement goal, Efe news reported.
In 2018, total carbon dioxide emissions were recorded at 1.24 billion tons, a year-on-year decrease of 3.6 per cent and the lowest figure since data compilation began in 1990, according to the preliminary figures released by the Japanese Ministry of Environment.
The previous low was recorded in 2009 with 1.25 billion tonnes of carbon dioxide.
Although this is the fifth consecutive year of dropping emissions, the ministry acknowledged that a lot remained to be done to achieve the 2030 goal of 26 percent cut in emissions from the 2013 levels a target set under the Paris climate agreement.
From 2013 to 2018, Japan's cumulative reduction in greenhouse gas emissions has been 11.8 percent, according to the government's figures published a week before the 2019 United Nations Climate Change Conference in Madrid.
The government said the main factors that contributed to the reduction were the decreasing production in power stations that use fossil fuels and gradual return to energy generation through nuclear plants.
Japan established a stricter safety framework following a nuclear standstill after the 2011 Fukushima accident.
Although the approval to reactivate was given in 2017, it was not until 2018 that the plants started functioning.
Household emissions fell by 10 percent in 2018 due to increased use of energy-saving appliances and a warm winter which led to lower usage of heating systems during the season.
However, an increased use of air conditioners caused a 9.4 percent rise in hydroflurocarbon emissions and other similar compounds.
The Japanese government aims to tackle this problem by introducing new regulations in 2020 to strengthen control over the disposal of hydroflurocarbon-using equipment.
( With inputs from IANS )