In this oscillator, an oscillation element 1, an IC chip 2, and a circuit element 3 composed as a discrete component such as a capacitor, etc. are integrally accommodated ina surface-mounted package 4 of a so-called H structure type.The surface-mounted package 4 is configured by comprising concave portions on both of its main surfaces, and by integrating an oscillation element 1, which is sealed w