Martinsville is a city in Clark County, Illinois, United States. The population was 1,167 at the 2010 census.
Martinsville is located at 39°20′18″N 87°52′55″W (39.338369, -87.881940).
According to the 2010 census, Martinsville has a total area of 2.08 square miles (5.39 km2), of which 2.05 square miles (5.31 km2) (or 98.56%) is land and 0.03 square miles (0.08 km2) (or 1.44%) is water.
As of the census of 2000, there were 1,225 people, 522 households, and 358 families residing in the city. As of 2018, the population had decreased to an estimated 1,104. The population density was 596.0 people per square mile (229.6/km2). There were 593 housing units at an average density of 288.5 per square mile (111.1/km2). The racial makeup of the city was 99.35% White, 0.16% Native American, 0.08% Asian, 0.08% from other races, and 0.33% from two or more races. Hispanic or Latino of any race were 0.24% of the population.
There were 522 households, out of which 31.0% had children under the age of 18 living with them, 54.2% were married couples living together, 9.2% had a female householder with no husband present, and 31.4% were non-families. 29.7% of all households were made up of individuals, and 15.9% had someone living alone who was 65 years of age or older.