Desired spectral characteristics are attained by making reflection films close enough. A variable spectroscopy device (1) has a pair of optical substrates (2, 3) opposing each other with an interval therebetween, two reflection films (5) opposing each other which are respectively disposed on opposing surfaces of the optical substrates (2, 3), two sensor electrodes (6) opposing each other which are disposed on the same surfaces as the reflection films (5) and which constitute an interval sensor for detecting an interval between the optical substrates (2, 3), and an actuator (4) which relatively moves the optical substrates (2, 3) and changes the interval between the optical substrates (2, 3). A distance between the opposing surfaces of the two sensor electrodes (6) is longer than a distance between the opposing surfaces of the two reflection films (5).