A printer apparatus is disclosed. The printer includes a medium feeding passage for conveying a medium; print head for performing a spacing and for performing a printing processing on the medium; a detector for detecting a first end position in a widthwise direction of the medium at a first position in a medium conveyance direction and for detecting a second end position in the widthwise direction of the medium at a second position in the medium conveyance direction; and a comparator for comparing the first end position with the second end position detected with the detector. The control of the print head is performed according to the compared result from the comparator.