An electronic component assembly includes an electronic component and a mounting board. The electronic component includes a stacked body, a pair of external electrodes provided on both end surfaces of the stacked body, and an insulating layer entirely covering a first main surface of the stacked body. The mounting board includes a board main body having a mounting surface, and land electrodes on the mounting surface. The first main surface of the electronic component faces the mounting surface of the mounting board, and the pair of external electrodes are mounted on the land electrodes with solder. Both end portions of the insulating layer in the length direction of the electronic component are located on the outer side relative to both end surfaces of the stacked body at least in a cross section taken at the center in the width direction.