The present invention pertains to a critical temperature indicator and a manufacturing method thereof. The critical temperature indicator may be mass-produced and indicates a red warning mark in the case of an improper maintenance state by monitoring a maintenance temperature profile from the first manufacturing instant to the final use of a frozen or chilled food as time lapses. An upper section is formed of a base film. A developing media member is formed of a micro-porous film to be positioned correspondingly to the upper section such that the developing media member is joined with the upper section. A time control section is formed by engraving a movement path of developing media on the developing media member by means of a printer, cutter or the like. At least one or more cutaway sections and a plurality of transparent members are positioned on the time control section, wherein the cutaway sections are positioned at both side surfaces of the time control section corresponding to the movement path so as to temporarily store the developing media, and the transparent members have linear- shaped first display windows so as to display the arrival of the developing media, which indicates the end of the movement of the developing media. An upper section is formed of a plurality of upper films and the upper films have second display windows and molded portions, wherein the second display windows are formed at positions in accordance with those of the first display windows, and the molded portions are formed to receive a developing material member.