There is provided a high-definition liquid crystal display device that can prevent flicker due to a reduction in the pixel potential in a low-frequency drive of about 10 Hz to reduce power consumption. The pixel has a TFT formed of Poly-Si as a switching element. In the pixel, a capacitance insulating film is formed on a planar first electrode on which a comb-shaped second electrode is formed. When the film thickness of the insulating film is d and the dielectric constant at 10 Hz frequency is ∈, it is given that ∈d≧5×10−6 m at 10 Hz frequency. The capacitance insulating film does not have a hysteresis characteristic. The refractive index of the capacitance insulating film with respect to a light of a wavelength of 632.8 nm is 1.7 to 2.0.