A trimmer head for a trimmer has a base member having a trimmer line opening. A clamping device arranged in the base member clamps a trimmer line that defines a cutting plane when rotated. The clamping member of the clamping device is rotatably disposed on a pivot bolt having a pivot axis positioned in a plane that is parallel to the cutting plane. The clamping member is spring-loaded by a clamping spring into a clamping position. The trimmer line is secured in the clamping position between a clamping surface and the clamping member. A centrifugal force acting on the trimmer line loads the clamping member in the clamping position. A U-shaped bracket has bracket legs connected by a stay. The clamping member is positioned between the bracket legs. The pivot bolt is supported on the bracket leg ends. The stay of the U-shaped bracket forms the clamping surface.