The average monthly wage in 2012, including bonuses and other irregular pay, fell to a record low ¥314,236, mainly due to an increase in the number of part-time workers, the government said Thursday.
The figure, down 0.6 percent from 2011, hit the lowest level since officials began compiling comparable data in 1990.
The drop reflected cuts in bonuses in the manufacturing sector affected by the yen's appreciation, a slowdown in the global economy and the March 2011 megaquake and tsunami.
The average pay for 2012 was about ¥57,000 lower than the all-time high of ¥371,670 in 1997, according to preliminary data from the Health, Labor and Welfare Ministry.
The regular monthly base wage slipped 0.1 percent from 2011 to ¥242,887, down for the seventh straight year. Bonuses and other special compensation dropped 3.1 percent to ¥52,586 for the first decrease in three years.
The ratio of part-time workers in the total labor force amounted to a record 28.75 percent, more than double the 12.97 percent registered in 1990. A labor ministry official attributed the decline in the average overall monthly wage to the increase in part-timers, and said the trend will likely continue for some time.
The monthly overtime pay and other nonbase pay rose 2.4 percent from a year earlier to ¥18,763 for the third consecutive year of increase.
Overtime work hours in the manufacturing sector, seen as a key index for measuring the state of the overall economy, gained 1.6 percent to 14.6 hours, up for the third year in a row.
For December alone, the average overall pay sank 1.4 percent from the previous year to ¥542,075 for the fourth straight month of decline. The regular monthly base wage edged down 0.2 percent to ¥242,854, down for the seventh straight month.
The figures were based on a survey of about 33,000 companies with at least five employees.