PURPOSE: To form display of letters, marks, etc., simply and exactly in a short time on an object molded of a thermoplastic resin by a method in which laser ray is projected onto a displaying object molded of a thermoplastic resin for melting to form a display.

CONSTITUTION: When laser ray is projected onto a displaying object 1 of a thermoplastic resin, a display 2 is clearly formed because the color of the melted portion is distinctly different from the other color of the displaying object 1. This can eliminate the needs to color the melted portion with a paint, etc., as in the case where laser ray is projected onto a metal plate. The formation of a display on a displaying object can thus be simply made in a short time at low cost.