Kummakivi (lit. 'odd stone' or 'strange stone') is a large balancing rock in Ruokolahti, Finland. The 7-metre (23 ft) long boulder lies on a convex bedrock surface with a very small footprint but so firmly that it cannot be rocked with human force.

According to scientific consensus, it was likely moved into its place by shifting masses of ice 11,000 to 12,000 years ago. Where exactly it originates from is unknown. Kummakivi has been protected since 1962. A pine tree originating from the 1980s grows on top of the boulder.

The boulder is located in a forest in the western part of the Ruokolahti municipality, near the border of Puumala.

• List of individual rocks

61°29′36″N 28°25′46″E / 61.4933°N 28.4294°E / 61.4933; 28.4294