A tape printer includes a thermal head (13) fixedly mounted on a frame (2) wherein the thermal head (13) prints character strings on a tape (5) uni-directionally moving past the thermal head (13). A keyboard (3) is provided for entering characters and data regarding a number of print lines. Character code data corresponding to the entered characters are temporarily stored in line buffer (41), and the thermal head (13 ) prints the character strings in a plurality of lines on the tape (5) based on the character code data and print line number data. Each of the plurality of print lines can be enhanced on a line basis with one of flush left, centering, flush right, and justification. When at least one of the plurality of lines is to be enhanced, the longest character string contained in one line is identified and the rest of the lines are printed in relevant positions referring to the print position of the longest character string.