忆阻器（英语：memristor /ˈmɛmrɨstər/），又名记忆电阻（英语：memory resistors），是一种被动电子组件。如同电阻器，忆阻器能产生并维持一股安全的电流通过某个设备。但是与电阻器不同的地方在于，忆阻器可以在关掉电源后，仍能「记忆」先前通过的电荷量。两组的忆阻器更能产生与晶体管相同的功能，但更为细小。最初于1971年，加州大学伯克利分校的蔡少棠教授根据电子学理论，预测到在电阻器、电容器及电感组件之外，还存在电路的第四种基本组件，即是忆阻器。 目前正在开发忆阻器的团队包括惠普、SK海力士、HRL实验室。

The memristor (/ˈmɛmrᵻstər/; a portmanteau of memory resistor) was a term coined in 1971 by circuit theorist Leon Chua as a missing non-linear passive two-terminal electrical component relating electric charge and magnetic flux linkage. The operation of RRAM devices was recently connected to the memristor concept. According to the characterizing mathematical relations, the memristor would hypothetically operate in the following way. The memristor's electrical resistance is not constant but depends on the history of current that had previously flowed through the device, i.e., its present resistance depends on how much electric charge has flowed in what direction through it in the past. The device remembers its history—the so-called non-volatility property. When the electric power supply is turned off, the memristor remembers its most recent resistance until it is turned on again.