A method of manufacturing a part-mounting package includes: forming a first through-hole in a first insulating sheet and forming a second through-hole whose opening area is larger than the first through-hole in a second insulating sheet; forming a penetration conductor covering an inner surface of the second through-hole and forming a conductor layer on a surface of at least the second insulating sheet; laminating the first insulating sheet and the second insulating sheet where center positions of the first through-hole and the second through-hole are matched to each other; causing linear laser division grooves to pass through a center of the first through-hole and the second through-hole; and dividing the sheet laminated body along the laser division grooves, and causing the side surface recess part and the end face through-hole conductor to appear.