A 0.2 percentage point drop in January's unemployment rate may be due to a new requirement that prevents some job-seekers from declaring themselves unemployed.

The seasonally adjusted unemployment rate fell to 5.3 percent in January from a revised record high of 5.5 percent in December, marking the first decline since February 2001.

However, as many as 200,000 jobless people might have been unable to count themselves as unemployed, said Eiji Shiraishi, chief researcher at the Japan Institute of Labor, an affiliate of the Health, Labor and Welfare Ministry.

In the survey, unemployed people are requested to select one of four reasons for seeking jobs: out of work involuntarily, out of work voluntarily, out of work after graduating from school and out of work for other reasons.

The number of men who chose the final option came to 320,000 in January, down 200,000 from a year earlier.

The falloff was surprising considering that in the past year this number had leveled off or rose by an average 100,000 a month.

According to Shiraishi, one possible reason behind the decline is that the labor ministry attached a new condition to the January survey -- that people choosing the fourth option must be in a situation where they need to earn money.

Shiraishi speculates the new condition might have prevented some indecisive job-seekers -- young adults living with their parents, for instance -- from making a choice, resulting in their being classified as not unemployed.

The drop of 200,000 is roughly equal to the 0.2 percentage point decline in the unemployment rate for January, he said, adding that without the new condition, the January rate would have been around 5.5 percent, unchanged from December.