Casting mold and manufacturing method of cast part

A manufacturing method of a heater unit for molding a cast part becoming the heater unit by filling molten metal into an internal space of a casting mold in which a heater is installed, wherein the casting mold is provided with:

• a molding wall portion configured to form the internal space;
• a supporting portion configured to support the heater to the molding wall portion;
• and
• a filling port configured to allow the molten metal to flow into the internal space, the heater has:
• a fixed portion configured to be supported by the casting mold;
• and
• an extending portion configured to be extended from the fixed portion, the internal space has:
• a supporting region configured to accommodate the fixed portion;
• and
• an extending region configured to accommodate the extending portion, the supporting region and the extending region are arranged so as to be aligned in a direction perpendicular to a flowing direction of the molten metal, and
• the manufacturing method comprising:
• an installation process of installing the heater in the casting mold;
• and
• a filling step of allowing the molten metal to flow into the internal space through the filling port, the filling port being configured to open to a portion of the molding wall portion facing the supporting region.