Method for bonding wafers

Provided is a method for bonding wafers, which is capable of bonding wafers with high reliability, while suppressing influence on the wafers. This method for bonding wafers comprises: a step for preparing a first wafer having a surface on which a first metal layer having a first stiffness is formed and a second wafer having a surface on which a second metal layer having a second stiffness that is higher than the first stiffness is formed; a step for removing an oxide film on the surface of the second metal layer without removing an oxide film on the surface of the first metal layer; and a step for bonding the surface of the first wafer with the surface of the second wafer.