A gain-controllable magnetoresistive analog amplifier includes a substrate in an X-Y plane, an output signal magnetoresistive sensor on the substrate, and an input signal coil and a gain adjustment coil. The input signal coil and the gain adjustment coil are respectively on two side surfaces of the sensor. The gain adjustment coil is used to input a gain signal by the generation of a gain magnetic field, in order to set the gain the magnetic field is applied along a magnetization direction of a free layer of the output signal magnetoresistive sensor. The input signal coil is used for inputting a current signal to generate an input magnetic field, in order to apply the input magnetic field to a magnetization direction of a pinned layer of the output signal magnetoresistive sensor. This amplifier provides isolation between input signals, output signals, and controllable gain signals.