The number grew by 13,452 to 451,514 last year, the first increase since 2000, the National Statistical Office said in its final report for the year.
The fertility rate, or the average number of babies that a woman gives birth to during her lifetime, advanced to 1.13 in 2006 from a record low of 1.08 a year earlier.
An increase in the number of marriages contributed to the rise in births, the office said.
After years of promoting family planning in the crowded nation, the government has become increasingly alarmed at the prospect of an ageing society -- with a huge pensions bill and too few workers to sustain economic growth.
In mid-2006 the government announced plans to spend a total of 18.9 trillion won (20 billion dollars) until 2010 to increase the number of nursery schools and provide more financial support for parents.
In the first seven months of this year, the number of births reached 238,817, up 5.1 percent year-on-year, according to separate government data.