Abstract: A magnetostrictive element that can exhibit a sufficiently large magnetostriction amount in a longitudinal direction is formed of a single crystal alloy magnetostrictive material. The magnetostrictive element has a shape of a plate-shaped rectangular parallelepiped, a main plane of the plate-shaped rectangular parallelepiped includes a plurality of magnetic domains that are regions where atomic magnetic moments are arranged in the same direction and whose width is 10 ?m to 200 ?m, and a total area rate of a magnetic domain where an angle difference between a lateral direction of the main plane and a direction of the magnetic moments of the magnetic domain is 10° or less to the main plane is 60% to 100%.

Abstract: Provided herein is an FeGa-base magnetostriction element that has specific characteristics with regards to magnetostriction along the longitudinal direction, and that shows a sufficiently high magnetostriction level along the longitudinal direction. The magnetostriction element is formed of a magnetostrictive material that is a monocrystalline alloy represented by Fe(100-?)Ga? (? represents the Ga content (at %), and satisfies 14???19) or Fe(100-?-?)Ga?X? (? and ? represent the Ga content (at %) and the X content (at %), respectively, X is at least one element selected from the group consisting of Sm, Eu, Gd, Tb, Dy, Cu, and C, and the formula satisfies 14???19, and 0.5???1).