In a method of bonding a first bump on a surface of a first member and a second bump on a surface of a second member, a tip portion of the first bump is provided with a projection having a hardness greater than a hardness of each of the first and second bumps. The first and second members are positioned with respect to each other such that the first and second bumps face each other. The tip portion of the first bump is brought into contact with a tip portion of the second bump by sticking the projection into the tip portion of the second bump.