A plurality of recording heads for ejecting inks of different colors are reciprocally moved relative to a recording medium, and printing operations are performed by executing main scans in forward and backward scans of the recording heads. In this case, an area printable in a single main scan is recorded by performing a plurality of main scans using a plurality of thinning patterns in which an m.times.n pixel group is defined as a unit pixel group, and the pixel groups are arranged at non-neighboring positions, and which have a complementary arrangement relationship therebetween. A high-quality color image free from time difference nonuniformity, and density nonuniformity caused by, e.g., variations of recording elements is obtained at high speed.