1. A printer having a recording head with plural recording elements being arranged in a main scan direction to record pixels on a recording paper, said recording head recording an image line by line while conveying said recording paper in a sub scan direction, said printer comprising: a sensor for detecting a lateral edge position of said recording paper in said main scan direction: a detecting section for detecting an edge recording element that is closest to said lateral edge position among said recording elements with the whole pixel in said recording paper; and a record control section for controlling said edge recording elements so as to decrease the recording density of an edge pixel corresponding to said edge heating element.