A sensing device includes a MEMS sensor and an adjustable amplifier. The MEMS sensor is configured to generate an input signal according to environmental changes. The adjustable amplifier has a first input terminal, a second input terminal, a third input terminal, a fourth input terminal and a first output terminal. The first input terminal is electrically connected to the MEMS sensor for receiving the input signal. The second input terminal is electrically connected to a first signal terminal for receiving a first common-mode signal. The third input terminal is electrically connected to the first output terminal. The fourth input terminal is electrically connected to a second signal terminal. An electric potential of a first output signal output by the first output terminal of the adjustable amplifier is related to electric potentials of the input signal, the first signal terminal and the second signal terminal.