Substrate processing apparatus

A substrate processing apparatus comprising:

• a chamber;
• a substrate supporting unit for supporting a substrate in the chamber;
• a gas injection unit including a plurality of first injection holes injecting a first process gas toward the substrate, and a gas inflow unit for communicating with the first injection holes and allowing the first process gas to flow in;
• a gas supply unit for supplying the first process gas to the gas injection unit, the gas supply unit including a gas supply connection unit connected with the gas inflow unit;
• and
• a sealing unit for maintaining sealing between the gas inflow unit and the gas supply connection unit,
• wherein the gas inflow unit comprises an insertion portion inserted into the gas supply connection unit, and
• the sealing unit is disposed outside the insertion portion to maintain sealing between the gas inflow unit and the gas supply connection unit.