An electronic component package includes: an insulating carrier substrate; a connection wiring that is provided on one side of the carrier substrate; an IC chip that is connected to the connection wiring; an external connection land that is disposed on the other side of the carrier substrate and is connected to the connection wiring via a wiring in the carrier substrate; and a solder ball that is disposed on the external connection land. A region of the external connection land that can be bonded to the solder ball has an outer shape that includes at least one arc portion and at least one straight portion. With this configuration, it is possible to provide an electronic component mounted apparatus in which bonding failure of the external connection land and the circuit board-side land with the solder ball can be reduced, and the bonding state can be easily inspected, and a method of inspecting a bonding portion therein.