Oscillator

An oscillator comprising:

• a piezoelectric element that outputs a signal with a predetermined oscillation frequency;
• a first package containing the piezoelectric element;
• an electronic element that controls the predetermined oscillation frequency by use of voltage;
• and
• a second package containing the electronic element and the first package,
• the second package including:
• a base in which the electronic element and the first package are mounted, and
• a lid that hermetically seals the electronic element and the first package with the base,
• wherein the base comprises
• a substrate part comprising a first major face and a second major face opposite to the first major face, the first major face being a major face on which the electronic element is mounted,
• a first frame part comprising a first frame face on which the first package is mounted, the first frame part being located on a peripheral edge of the first major face, and
• a second frame part comprising a second frame face to which the lid is joined, the second frame part being located on a peripheral edge of the first frame face,
• wherein the first major face and the first frame face have a difference in level,
• wherein the first package is mounted not on the electronic element but on the first frame face,
• wherein the electronic element is mounted on the first major face such that the electronic element is partially located in a spare space between the first package and the first major face, and
• wherein the piezoelectric element contained in the first package does not entirely cover the electronic element.