Martinsville is a city in Clark County, Illinois, United States.

[3] As of the 2020 census[5] there were 1,118 people, 526 households, and 376 families residing in the city.

The population density was 545.63 inhabitants per square mile (210.67/km2).

There were 526 households, out of which 36.7% had children under the age of 18 living with them, 43.16% were married couples living together, 14.64% had a female householder with no husband present, and 28.52% were non-families.

26.05% of all households were made up of individuals, and 14.83% had someone living alone who was 65 years of age or older.