A printing apparatus comprises: a transport mechanism that transports a recording medium; a first line head group including a first line head in number of N that ejects first ink; a second line head group including a second line head in number of M that ejects second ink; and a controller, where M is a natural number larger than N. The line heads form images along lines extending in a width direction along a surface of the recording medium by ejecting ink droplets from a plurality of nozzles aligned in the width direction. In a first printing step, the controller makes each of the first line head in number of N perform printing process on every N-th line, while making each of the second line heads in number of M perform the printing process on every M-th line.