磁芯内存（英语：Magnetic Core Memory）是一种早期的电脑内存。磁芯内存是利用磁性材料制成之内存，其原理为：将磁环（磁芯）带磁性或不带磁性之状态，用以代表1或0之比特，一长串1或0之组合就代表要保存之信息。

磁芯内存是一种随机访问内存（Random Access Memory），在电脑中可担任主内存的角色。 比起真空管而言，磁芯内存省电、也没有真空管的寿命问题。当电脑进入半导体时代后，仍然有一段相当的时间，磁芯内存持续担任主内存的角色。又由于磁芯内存是非挥发性内存（Non-volatile Memory），它的一个特色是：即使当机或电源中断，只要没有发生错误的写入信号，则仍然可保有其内容。

Magnetic-core memory was the predominant form of random-access computer memory for 20 years between about 1955 and 1975. Such memory is often just called core memory, or, informally, core.

Core uses tiny magnetic toroids (rings), the cores, through which wires are threaded to write and read information. Each core represents one bit of information. The cores can be magnetized in two different ways (clockwise or counterclockwise) and the bit stored in a core is zero or one depending on that core's magnetization direction. The wires are arranged to allow for an individual core to be set to either a one or a zero and for its magnetization to be changed by sending appropriate electric current pulses through selected wires. The process of reading the core causes the core to be reset to a zero, thus erasing it. This is called destructive readout. When not being read or written, the cores maintain the last value they had, even when power is turned off. This makes them nonvolatile.