An infrared image sensor for detecting infrared rays, the infrared image sensor comprising: a light-receiving unit including a pixel region in which a plurality of pixels are arranged and at least one reference pixel; a plurality of integrating amplifiers, each of the plurality of integrating amplifiers being connected to a respective pixel line of the light-receiving unit; a difference circuit for acquiring a first differential signal that is a differential signal between a signal of one pixel contained in a first pixel line and a signal of the reference pixel by using an integrating amplifier corresponding to the first pixel line and a second differential signal that is a differential signal between signals of two predetermined pixels out of the pixels contained in the first pixel line by using said integrating amplifier corresponding to the first pixel line; a pixel signal calculating unit that calculates a signal of each of the pixels on the basis of the first differential signal and the second differential signal; wherein each of the plurality of integrating amplifiers being electrically connected to each pixel in the respective pixel line through respective switches (S 0, S 1,...S m); the infrared image sensor wherein the two predetermined pixels are connected in series with respective first ends thereof connected to each other and also with respective second ends connected to different potentials (V, GND), and the difference circuit acquires the second differential signal on the basis of a difference between a potential at the connecting point of the two predetermined pixels and a predetermined potential (Vm) by connecting the integrating amplifier to a connection point of the two predetermined pixels and inputting the predetermined potential (Vm) into the integrating amplifier. a light-receiving unit including a pixel region in which a plurality of pixels are arranged and at least one reference pixel; a plurality of integrating amplifiers, each of the plurality of integrating amplifiers being connected to a respective pixel line of the light-receiving unit; a difference circuit for acquiring a first differential signal that is a differential signal between a signal of one pixel contained in a first pixel line and a signal of the reference pixel by using an integrating amplifier corresponding to the first pixel line and a second differential signal that is a differential signal between signals of two predetermined pixels out of the pixels contained in the first pixel line by using said integrating amplifier corresponding to the first pixel line; a pixel signal calculating unit that calculates a signal of each of the pixels on the basis of the first differential signal and the second differential signal; wherein each of the plurality of integrating amplifiers being electrically connected to each pixel in the respective pixel line through respective switches (S 0, S 1,...S m); the infrared image sensor wherein the two predetermined pixels are connected in series with respective first ends thereof connected to each other and also with respective second ends connected to different potentials (V, GND), and the difference circuit acquires the second differential signal on the basis of a difference between a potential at the connecting point of the two predetermined pixels and a predetermined potential (Vm) by connecting the integrating amplifier to a connection point of the two predetermined pixels and inputting the predetermined potential (Vm) into the integrating amplifier.