Kōka (甲賀郡 Kōka-gun?) was a district located in Shiga Prefecture, Japan.
As of 2003, the district had an estimated population of 147,928 and a density of 267.90 persons per km². The total area was 552.18 km².
Before the dissolution in 2004, the district had seven towns as listed below. Each municipality is now a part of the city noted in the parentheses.