To provide a primary rust-proof coating material composition in which the flash point of a second component at one atmospheric pressure is set to ≥21°C, the restriction of designated quantity based on the fire laws is mitigated and both of drying property and hardenability at a low temperature are excellent.

The primary rust-proof coating material composition contains (A) a first component containing a siloxane-based bonder (a1) and (B) a second component which contains zinc powder (b1) and an acetic acid ester solvent (b2) having the flash point of ≥21°C at one atmospheric pressure, and has the flash point of ≥21°C at one atmosphere.