In a method for forming bumps 19 on electrodes 32 of a wiring board 31, a fluid 14 containing conductive particles 16 and a gas bubble generating agent is supplied onto a first region 17 including the electrodes 32 on the wiring board 31. Then, a substrate 40 which has a protruding surface 13 having the same area as that of the first region 17 and formed on a main surface 18 of the substrate 40 having a larger area than that of the first region 17 is disposed so that the protruding surface 13 faces the first region 17 of the wiring board 31. Then, the fluid 14 is heated to generate gas bubbles 30 from the gas bubble generating agent contained in the fluid 14.