The deterioration came partly because people who had temporarily given up searching for jobs, especially women, started to do so again.
While the number of people employed stood at 62.46 million, unchanged from September, the number of the unemployed was up by 250,000, or 9.4 percent, to 2.92 million.
The non-workforce population, meanwhile, was down by 220,000, or 0.5 percent, to 44.96 million.
The jobless rate for men in the reporting month rose to 4.8 percent from 4.4 percent, while that for women grew to 4.0 percent from 3.6 percent.
Data from Iwate, Miyagi and Fukushima prefectures, which were hardest hit by the March 11 earthquake and tsunami, started to be included again in the nationwide survey from the September report.
Compared with a year earlier, the number of jobless people fell 460,000 to 2.88 million in October.
Separate data by the Health, Labor and Welfare Ministry showed the nation's job availability was flat in October from a month before, with the ratio of employment offers to seekers standing at 0.67. This means 67 posts were available for every 100 seekers.