Adherens junctions (AJs), which are organized by adhesion proteins and the underlying actin cytoskeleton, probably sense pulling forces from adjacent cells and modulate opposing forces to maintain tissue integrity, but the regulatory mechanism remains unknown at the molecular level. Although the possibility that alpha-catenin acts as a direct linker between the membrane and the actin cytoskeleton for AJ formation and function has been minimized, here we show that alpha-catenin recruits vinculin, another main actin-binding protein of AJs, through force-dependent changes in alpha-catenin conformation. We identified regions in the alpha-catenin molecule that are required for its force-dependent binding of vinculin by introducing mutant alpha-catenin into cells and using in vitro binding assays. Fluorescence recovery after photobleaching analysis for alpha-catenin mobility and the existence of an antibody recognizing alpha-catenin in a force-dependent manner further supported the notion that alpha-catenin is a tension transducer that translates mechanical stimuli into a chemical response, resulting in AJ development.