Manufacturing method of supporting structure for vehicle

A manufacturing method of a supporting structure for vehicle, the supporting structure for vehicle including:

• a first fixing portion to which an object to be supported is fixed;
• a second fixing portion which is fixed to a vehicle body;
• and
• a connecting portion for connecting the first fixing portion with the second fixing portion, wherein
• when a load not less than a predetermined value is given to the object to be supported, the connecting portion is plastically deformed by the load,
• the manufacturing method comprising:
• preparing a casting mold comprising:
• a first and a second casting mold, which are matched to each other at the time of casting, and comprises forming faces which form at least sides of the first fixing portion, the second fixing portion and the connecting portion;
• and
• a third casting mold comprising:
• a forming face which forms a fixing face of the second fixing portion;
• and
• a protruding body which forms a recess hole penetrating to an interior of the connecting portion from the fixing face of the second fixing portion;
• matching the third casting mold together with the first and the second casting mold so as to form a cavity for integrally forming the first fixing portion, the second fixing portion and the connecting portion in the casting mold;
• and
• pouring molten metal into the cavity so as to mold the supporting structure.