To provide a semiconductor device stable in operation of a transistor for a long term use, to provide a liquid crystal display panel, to provide an electronic instrument equipped therewith, and to provide the manufacturing method of the semiconductor device.

The transistor T5 is used in such a manner that the absolute value of its threshold voltage varies in its increasing direction, and the transistor T6 is used as varying in its decreasing direction. Phosphorus is injected in the channel regions 5 and 6 of the transistors T5 and T6 with concentration of 11012 cm-2 and 31012 cm-2 respectively. Consequently, the absolute value of the threshold voltage is made smaller in the transistor T5 at the beginning of its manufacture than that in the transistor T6.