To provide a liquid crystal display device provided with a satisfactory auxiliary capacitance without reducing the aperture ratio.

A pixel electrode 23 is formed on one of a pair of substrates 1 and 2. An another electrode forming a liquid crystal capacitance between the another electrode and the pixel electrode is provided. An auxiliary capacitance is connected in parallel with the liquid crystal capacitance. The liquid crystal display device having a liquid crystal 3 interposed between the pair of substrates 1 and 2 is provided. An insulating film is formed on a semiconductor layer 20 for the auxiliary capacitance and an auxiliary capacitance line 21 is formed on the insulating film to form the auxiliary capacitance. Ruggedness is formed on the surface of the semiconductor layer 20 for the auxiliary capacitance. The height of the ruggedness is suppressed to the height equal to the thickness of a gate insulating film 15 or below. The liquid crystal display device provided with the large auxiliary capacitance is obtained, wherein a leakage defect between the semiconductor layer 20 for the auxiliary capacitance and the auxiliary capacitance line 21 is not generated and the aperture ratio is not reduced.