A shutter operation state monitoring method performed in a thermal imaging camera includes, controlling a shutter of the thermal imaging camera to be closed, capturing a first thermal image, calculating a correction offset value for the first thermal image, controlling the shutter to be opened, capturing a second thermal image, applying the correction offset value to the second thermal image, measuring a sound with a microphone when controlling the shutter to be closed and/or when controlling the shutter to be opened, determining whether the measured sound matches an operation sound of the shutter, and outputting an alarm indicating malfunction of the shutter if the measured sound does not match the operation sound.