An imaging device has an optical low-pass filter and a solid-state image sensor. The optical low-pass filter includes a plurality of birefringent plates. When a plurality of spaced spots formed by the birefringent plates with respect to incident light are located at adjacent positions such as to be regarded as one spot on the birefringent plates, the birefringent plates are constructed so that a phase difference between light waves passing through the plurality of spaced spots with respect to any wavelength in a visible wavelength region is larger than the wavelength. Thus, the imaging device, even when using many quartz filters, makes the intensities of the spaced spots uniform and can secure the optical low-pass filter free of dependence of wavelength.