Package for accommodating electronic element, and electronic device

A package for accommodating an electronic element, comprising:

• a base comprising a wall and an accommodating portion surrounded by the wall;
• a coaxial line located in the wall;
• and
• a signal line connected to the coaxial line on a side of the wall, wherein
• the coaxial line comprises a pin terminal protruding from the wall,
• the signal line comprises an insulation plate comprising a first surface and a second surface on a side opposite to the first surface, a signal conductor located on the first surface and connected to the pin terminal, first ground conductors located on the first surface with the signal conductor interposed between the first ground conductors, and a second ground conductor located on the second surface,
• the signal line includes, in order from the coaxial line side, a first section, a second section, and a third section,
• a width of the signal conductor in the second section is constant, is less than or equal to a width of the signal conductor in the first section, and is greater than a width of the signal conductor in a center portion of the third section,
• a distance between the signal conductor and each of the first ground conductors is constant in the second section, is less than the distance in the first section, and is greater than the distance in the center portion of the third section, and
• the second section has a length of from ⅓ times to 3/2 times a distance H between the signal conductor and the second ground conductor on a side opposite to the coaxial line from a position at which a distal end portion of the pin terminal is present as viewed in a direction perpendicular to the first surface.