A separating method of a bonded body, the bonded body including two base members and a bonding film through which the base members are boded together, enabling to easily and efficiently separating the bonded body into the two original base members is provided. Further, the bonding film contains a silicone material composed of silicone compounds. The separating method includes: preparing the bonded body with the bonding film; and applying energy for separation to the bonding film so that cleavage is generated within the bonding film due to breakage of a part of molecular bonds of the silicone compounds, to thereby separate the bonded body into the first and second base members.