By product, output of automobiles jumped 8.7% and semiconductors rose 4.4% over the month, whereas communication devices slumped 16.9%.
The finance ministry said the data showed the economy was on a recovery path after a slight correction the previous month.
Factory output will rebound in the second quarter after four consecutive quarters of loss as exports bottom out, the ministry said.
South Korea's heavily trade-reliant economy barely averted a recession with growth of 0.3% in the first quarter, after contracting in late 2022 for the first time in 2-1/2 years.
Retail sales rose 0.4% in May, after dropping 2.6% in April - which was the worst in five months - while facility investment jumped 3.5%, the most since August.
Persons:
Kang Min Joo, Kang, Jihoon Lee, Jacqueline Wong, Christopher Cushing
Organizations:
Statistics, ING Economics, Thomson
Locations:
SEOUL, Statistics Korea