<p>A fixation section (21) of a shielding plate (20) is fixed to the vicinity of the lower end edge of an opening (15) of a casing (1). Of the portions of the shielding plate (20), a portion of a step section (22) continuous to the fixation section (21), a flat section (23), and a bent section (24) are placed in the casing (1). The tip of the bent section (24) is in contact with an inner surface near the upper end of the opening (15). Entry of a flame into the casing (1) from the upper end of the opening (15) is prevented. A gap as an air passage is formed between the side edge of the opening (15) and the flat section (23), so that airflow can reach the inside of the casing (1) to improve cooling efficiency of an electrical component in an electrical-component box (10).</p>
