To provide an automatic painting method for executing panting on a painting object automatically and efficiently.

An apparatus using the automatic painting method comprises first and second painting object fitting implements 22a, 22b, which reciprocate on first and second guides 19a, 19b arranged in V-shape, respectively, a painting gun 13 which reciprocates on an intermediate guide 11 arranged in the middle between the first and second guides, and gussets 1a, 1b fitted on the first and second painting object fitting implements in a removable manner, respectively. As the first and second painting object fitting implements are reciprocated alternately on the first and second guides, the painting gun is made to approach the gusset fitted on the painting object fitting implement that is positioned at the apex of the V-shape, and primer and paint are sprayed sequentially from the nozzles 14, 15 of the painting gun to paint the gusset.