Semiconductor device

A semiconductor device comprising:

• a substrate;
• an oxide semiconductor layer that is spaced from the substrate in a first direction intersecting with a surface of the substrate and contains a first metal element and oxygen (O);
• a first wiring opposed to a part of the oxide semiconductor layer;
• a gate insulating film disposed between the oxide semiconductor layer and the first wiring;
• a first conductive layer that is in contact with one end in the first direction of the oxide semiconductor layer and contains a second metal element and oxygen (O);
• a second wiring electrically connected to the first conductive layer;
• and
• a first insulating portion in contact with the second wiring, wherein
• the first insulating portion includes:
• a first region;
• and
• a second region between the first region and the second wiring, and
• a concentration of the first metal element in the second region is higher than a concentration of the first metal element in the first region, or a concentration of the second metal element in the second region is higher than a concentration of the second metal element in the first region.