To provide a bonding method capable of improving the bonding reliability of Au-Si eutectic bonding.

In a method for bonding two substrates 1, 2 by Au-Si eutectic bonding, a first substrate 1 formed by using a first silicon substrate 10 and a second substrate 2 formed by using a second silicon substrate 20 are prepared. Under a state that a load is impressed on two substrates 1, 2 superimposed so that an Au membrane 13 of the first substrate 1 and the second silicon substrate 20 of the second substrate 2 are contacted in the chamber of a bonding apparatus; a temperature elevating step for elevating the temperature for two substrates 1, 2 to a specified temperature higher than an Au-Si eutectic temperature, a temperature holding step for holding the heating temperature for two substrates 1, 2 at the specified temperature for a predetermined time, and a temperature lowering step for lowering the temperature for two substrates 1, 2 to room temperature, are successively carried on. In the temperature lowering step, two substrates 1, 2 are rapidly cooled down from the specified temperature.