Lopaca (pronounced [lɔˈpaːtsa]) is a village in the Municipality of Šentjur in eastern Slovenia. It lies just off the regional road leading south out of Šentjur towards Kozje. The area is part of the historical Styria region. The municipality is now included in the Savinja Statistical Region.
The local parish church is dedicated to Saint Anne and belongs to the Roman Catholic Diocese of Celje. It was built in the early 19th century on the site of a 15th-century predecessor.