SEALING MEMBER FOR ELECTRONIC COMPONENT PACKAGE, ELECTRONIC COMPONENT PACKAGE, AND ELECTRONIC COMPONENT

PROBLEM TO BE SOLVED: To improve the strength of a sealing member for an electronic component package which is used as a second sealing member of an electronic component package hermetically sealing an electrode of an electronic component element with a first sealing member and the second sealing member and has a cavity for housing the electronic component element.SOLUTION: A sealing member for an electronic component package 7 includes a cavity 75 enclosed by a top part 71 and a wall part 73 provided along an entire outer peripheral edge of one main surface 72 of the top part 71. The one main surface 72 of the top part 71 has long sides 721, 722 and short sides 723, 724. The wall part 73 has a first long side part 81 arranged along the long side 721 of the one main surface 72 and a second long side part 82 facing the first long side part 81. In at least one of the first side part 81 and the second long side part 82, center parts 812, 822, respectively including center points C1, C2, are formed so as to be wider compared to at least one of both end parts 811, 813, 821, 823.