在这篇文章内，矢量与标量分别用粗体与斜体显示。例如，位置矢量通常用表示；而其大小则用来表示。

磁化强度（英语：magnetization），又称磁化矢量，是衡量物体的磁性的一个物理量，定义为单位体积的磁偶极矩，如下方程序：

其中， 是磁化强度， 是磁偶极子密度， 是每一个磁偶极子的磁偶极矩。

当施加外磁场于物质时，物质的内部会被磁化，会出现很多微小的磁偶极子。磁化强度描述物质被磁化的程度。采用国际单位制，磁化强度的单位是安培／公尺。

物质被磁化所产生的磁偶极矩有两种起源。一种是由在原子内部的电子，由于外磁场的作用，其轨域运动产生的磁矩会做拉莫尔进动，从而产生的额外磁矩，累积凝聚而成。另外一种是在外加静磁场后，物质内的粒子自旋发生「磁化」，趋于依照磁场方向排列。这些自旋构成的磁偶极子可视为一个个小磁铁，可以以矢量表示，作为自旋相关磁性分析的古典描述。例如，用于核磁共振现象中自旋动态的分析。

In classical electromagnetism, magnetization (magnetisation in British English) or magnetic polarization is the vector field that expresses the density of permanent or induced magnetic dipole moments in a magnetic material. The origin of the magnetic moments responsible for magnetization can be either microscopic electric currents resulting from the motion of electrons in atoms, or the spin of the electrons or the nuclei. Net magnetization results from the response of a material to an external magnetic field, together with any unbalanced magnetic dipole moments that may be inherent in the material itself; for example, in ferromagnets. Magnetization is not always uniform within a body, but rather varies between different points. Magnetization also describes how a material responds to an applied magnetic field as well as the way the material changes the magnetic field, and can be used to calculate the forces that result from those interactions. It can be compared to electric polarization, which is the measure of the corresponding response of a material to an electric field in electrostatics. Physicists and engineers usually define magnetization as the quantity of magnetic moment per unit volume. It is represented by a pseudovector M.