趋磁细菌（英语：Magnetotactic bacteria，缩写MTB）是细菌中的一个多系群，由Richard P. Blakemore于1975年发现，能感应地磁场的磁感线。为达到这一功能，这些细菌拥有一个叫作磁小体的细胞器来贮存磁性晶体。这些微生物会定向移动来响应环境磁场的现象被称为趋磁性，有南趣（south-seeking）与北趣（north-seeking）（趣通趋）两种趋磁行为。和动物的磁感应相比，这些带有磁铁的细菌还能定向排列（甚至包括死细胞），就像指南针一样，这被认为能有助于这些细菌达到最佳的氧浓度区域。

Magnetotactic bacteria (or MTB) are a polyphyletic group of bacteria discovered by Richard P. Blakemore in 1975, that orient along the magnetic field lines of Earth's magnetic field. To perform this task, these bacteria have organelles called magnetosomes that contain magnetic crystals. The biological phenomenon of microorganisms tending to move in response to the environment's magnetic characteristics is known as magnetotaxis (although this term is misleading in that every other application of the term taxis involves a stimulus-response mechanism). In contrast to the magnetoception of animals, the bacteria contain fixed magnets that force the bacteria into alignment — even dead cells align, just like a compass needle. The alignment is believed to aid these organisms in reaching regions of optimal oxygen concentration.