PURPOSE: To provide an electric connection box equipped with an element operation confirmation window capable of easily confirming the operating conditions of a PTC element from the outside of the electric connection box having a built-in circuit arranged with a PTC element.

CONSTITUTION: A detecting piece 7 having a temperature indicating material 9, which changes color by heating, is projected out from an electrode 5 of a PTC element 1, this detecting piece 7 is inserted to an element operation conformation window 10 opened in a case 2 of an electric connection box, and any color change on the temperature indicating material 9 attached to the detecting piece 7 can be confirmed by visually looking at the element operation confirmation window 10 from the outside of the electric connection box.