Johnstown is a town in Polk County, Wisconsin, United States.

At the 2000 census there were 520 people in 203 households, including 154 families, in the town.

There were 418 housing units at an average density of 11.7 per square mile (4.5/km2).

The racial makeup of the town was 81.15% White, 18.27% Native American, 0.58% from two or more races.

Out of the total population, 22.3% of those under the age of 18 and 6.8% of those 65 and older were living below the poverty line.