To provide an electronic component mounting device capable of excellently pressure-joining a bump.

An electronic component mounting device includes: a first tool 5 which has a first region I where a first electronic component 20 having a first bump 21 on an upper side is placed thereon, and has a first projection 4f formed along an edge of the first region I and restricting a movement of the first electronic component 20 in a first lateral direction; a stage 3 which is provided with the first tool 5 thereon, and can move laterally; a second tool 8 which has a second region II where a second electronic component 30 having a second bump 31 joined to the first bump 21 is supported, and has second projections 7f and 7g formed along an edge of the second region II and restricting a movement of the second electronic component 30 in a second lateral direction opposite to the first lateral direction; a bonding arm 6 which is provided with the second tool 8 thereunder, and can move longitudinally; and arm driving parts 10 and 11 which move the bonding arm 6 longitudinally.