A semiconductor device structure is provided. The semiconductor device structure includes an insulating layer over a substrate, a gate stack formed in the insulating layer, and an insulating capping layer formed in the insulating layer to cover the gate stack. The semiconductor device structure also includes a source/drain contact structure adjacent to the gate stack. The source/drain contact structure has a sidewall that is in direct contact with a sidewall of the insulating capping layer, and an upper surface that is substantially level with an upper surface of the insulating capping layer and an upper surface of the insulating layer. In addition, the semiconductor device structure includes a first via structure above and electrically connected to the gate stack and a second via structure above and electrically connected to the source/drain contact structure.