Barangay Mainit

Classified as a small barangay, Barangay Mainit is one of the administrative divisions of Boac in Marinduque, MIMAROPA Region, Philippines.

According to the 2020 Philippine census, Barangay Mainit had a population of 1,013. This made it the 25th largest of 61 barangays in Boac by population, placing it in the middle tier of the municipality. Residents of Barangay Mainit accounted for approximately 1.77% of the total population of Boac, which stood at 57,283 in the same census year.

The barangay recorded 852 residents in the 2015 intercensal count and 1,013 residents in the 2020 Census — a net change of +18.9%, consistent with a growing settlement. Barangay Mainit is officially classified as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

Boac is a municipality comprising 61 barangays, and serves as the governing unit directly responsible for local services in Barangay Mainit, including public health, sanitation, peace and order, and civil registration. Within the wider province of Marinduque, which contains 218 barangays across its component cities and municipalities, Barangay Mainit ranks 95th by 2020 population. Marinduque is classified as a 4th by the Bureau of Local Government Finance, a category that reflects the province's annual regular income.

Like every Philippine barangay, Barangay Mainit is led by an elected Punong Barangay (barangay captain) supported by seven Sangguniang Barangay members (kagawads), an SK Chairperson, a Barangay Secretary, and a Barangay Treasurer. The next Barangay and Sangguniang Kabataan Elections (BSKE) are scheduled for Monday, November 2, 2026, with officials serving four-year terms under Republic Act No. 12232.