磁致伸缩效应（英语：magnetostrictive effect）指的是对软磁体进行磁化后，其形状、大小会发生变化的物理现象,该现象在19世纪中叶被人们发现。磁致伸缩现象具有各向异性。当长度为l的磁性材料在磁化方向上的长度变化为Δl时，磁致伸缩率可表示为：λ=Δl/l。由于磁致伸缩率一般在10以下，所以对磁致伸缩效应的应用远不如对压电效应的应用广泛。到20世纪60、70年代后，发现了伸缩率在10的超磁致伸缩材料。磁致伸缩效应才重新受到重视。

Magnetostriction (cf. electrostriction) is a property of ferromagnetic materials that causes them to change their shape or dimensions during the process of magnetization. The variation of materials' magnetization due to the applied magnetic field changes the magnetostrictive strain until reaching its saturation value, λ. The effect was first identified in 1842 by James Joule when observing a sample of iron.