A semiconductor package includes: a semiconductor element mounted on a one-sided plane of a wiring board; an underfill agent dropped so as to be filled between the semiconductor element and the wiring board; and a pad group constituted by a plurality of pads which are formed in the vicinity of a circumference of the wiring board and along the circumference, the pad group being formed on a bottom plane of a groove portion formed in a solder resist which covers the one-sided plane of the wiring board, wherein a corner edge of the groove portion located in the vicinity of a dropping starting portion to which dropping of the underfill agent is started is formed at an obtuse angle or in an arc shape in order to avoid the dropped underfill agent from entering into an inner portion of the groove portion.