A junction field effect transistor semiconductor device comprising: a wafer having at least one main surface made of silicon carbide; and an electrode formed on said one main surface, said wafer including an ion implantation region formed to include said one main surface, said ion implantation region including a base region disposed to include said one main surface, and a protruding region connected to said base region and extending in a direction opposite to said electrode, said base region being greater in width in a direction along said one main surface than said protruding region, said electrode being disposed in contact with said ion implantation region such that said electrode is entirely located on said ion implantation region as seen in plan view; said electrode is a gate electrode; said wafer includes a first layer of a first conductivity type, a layer of a second conductivity type which is different in conductivity type from said first layer of the first conductivity type, and disposed on and in contact with said first layer of the first conductivity type, and a second layer of the first conductivity type which is identical in conductivity type to said first layer of the first conductivity type, and disposed on and in contact with said layer of the second conductivity type, and said ion implantation region extends to said layer of the second conductivity type, wherein in said second layer of the first conductivity type and said layer of the second conductivity type, a first impurity region and a second impurity region being of the second conductivity type and including impurities higher in concentration than said layer of the second conductivity type are formed, said first impurity region, said ion implantation region and said second impurity region extend through said second layer of the first conductivity type to said layer of the second conductivity type. a wafer having at least one main surface made of silicon carbide; and an electrode formed on said one main surface, said wafer including an ion implantation region formed to include said one main surface, said ion implantation region including a base region disposed to include said one main surface, and a protruding region connected to said base region and extending in a direction opposite to said electrode, a base region disposed to include said one main surface, and a protruding region connected to said base region and extending in a direction opposite to said electrode, said base region being greater in width in a direction along said one main surface than said protruding region, said electrode being disposed in contact with said ion implantation region such that said electrode is entirely located on said ion implantation region as seen in plan view; said electrode is a gate electrode; said wafer includes a first layer of a first conductivity type, a layer of a second conductivity type which is different in conductivity type from said first layer of the first conductivity type, and disposed on and in contact with said first layer of the first conductivity type, and a second layer of the first conductivity type which is identical in conductivity type to said first layer of the first conductivity type, and disposed on and in contact with said layer of the second conductivity type, and a first layer of a first conductivity type, a layer of a second conductivity type which is different in conductivity type from said first layer of the first conductivity type, and disposed on and in contact with said first layer of the first conductivity type, and a second layer of the first conductivity type which is identical in conductivity type to said first layer of the first conductivity type, and disposed on and in contact with said layer of the second conductivity type, and said ion implantation region extends to said layer of the second conductivity type, wherein in said second layer of the first conductivity type and said layer of the second conductivity type, a first impurity region and a second impurity region being of the second conductivity type and including impurities higher in concentration than said layer of the second conductivity type are formed, said first impurity region, said ion implantation region and said second impurity region extend through said second layer of the first conductivity type to said layer of the second conductivity type.