n regions 3 is shown in fig2 sectional portions of the n regions 4 and 5 can be shown in the same manner as in fig2 except that the n region 3 shown in fig2 is replaced by an n region 4 or 5 and the pixel electrode film 14 connected by the vertical wire 26 is replaced by the pixel electrode film 18 in the case of the n region 4 or by the pixel electrode film 22 in the case of the n region 5 accordingly the description of the sectional portions of the n regions 4 and 5 will be omitted referring back to fig2 an n region 6 which is an n type impurity region extending in the y direction and being lower in density than the n region 3 is formed in the right of the n region 3 so as to be slightly apart from the n region 3 an n region 9 equivalent to a second impurity region in the scope of claim which is an n type impurity region lower in density than the n region 3 is formed under the n region 3 the n region 3 and the n region.