A formaldehyde detecting apparatus includes a formaldehyde sensor configured to measure concentration of formaldehyde in air; a printed circuit board on which the formaldehyde sensor is disposed, the printed circuit board including a signal processor configured to process a signal output from the formaldehyde sensor; a fixing member disposed on the printed circuit board, the fixing member configured to fix the formaldehyde sensor, wherein the fixing member prevents the formaldehyde sensor from oscillating with respect to the printed circuit board by external vibration; and a power supply configured to supply a voltage capable of stabilizing an output signal to the signal processor.