A semiconductor device which can suppress leakage current between a wiring and a connection electrode connected to a floating node is provided. The semiconductor device includes a first insulator, a first conductor over the first insulator, a second conductor over the first insulator, and a second insulator over the first insulator, the first conductor, and the second conductor. The first conductor and the second conductor contain a metal A (one kind or a plurality of kinds of aluminum, copper, tungsten, chromium, silver, gold, platinum, tantalum, nickel, molybdenum, magnesium, beryllium, indium, and ruthenium). The metal A is detected in an interface between the first insulator and the second insulator by an energy dispersive X-ray spectroscopy (EDX). The second insulator includes a groove for exposing the first insulator between the first conductor and the second conductor.