A package of a surface-mountable electronic component to be reflow-soldered to a circuit board at about 250.degree. C. or more includes a case and a cover. The cover has a softening temperature lower than the reflow temperature, and the case has a softening temperature higher than the reflow temperature. In the package, softening the cover compensates for the stress on the bonded surfaces resulting from a difference in thermal expansion between the case and the cover caused during reflow.