An atomic oscillator comprising: a plurality of components, the plurality of components including a light source that emits excitation light, a gas cell in which an atom to be excited by the excitation light is sealed, a spacer , located between the gas cell and the light source , and a photodetector that detects the excitation light transmitting through the gas cell, the photodetector including connecting terminals ; and a main part , in which at least some of the plurality of components are laminated, wherein: the spacer and the gas cell are adjacent to each other in the main part; an electrically conductive film is formed on each of side surfaces of the spacer and the gas cell ; a bonding surface of the spacer and a bonding surface of the gas cell face each other; and a bonding pattern , that extends from the electrically conductive film , is formed on the bonding surface of the spacer , and a bonding pattern , that extends from the electrically conductive film , is formed on the bonding surface of the gas cell , and the bonding patterns that face each other are bonded by a bonding material ; such that the connecting terminals are respectively connected to pads formed on an insulating film through, at least, the electrically conductive films formed on the side surfaces of the spacer and the gas cell . a plurality of components, the plurality of components including a light source that emits excitation light, a gas cell in which an atom to be excited by the excitation light is sealed, a spacer , located between the gas cell and the light source , and a photodetector that detects the excitation light transmitting through the gas cell, the photodetector including connecting terminals ; and a light source that emits excitation light, a gas cell in which an atom to be excited by the excitation light is sealed, a spacer , located between the gas cell and the light source , and a photodetector that detects the excitation light transmitting through the gas cell, the photodetector including connecting terminals ; and a main part , in which at least some of the plurality of components are laminated, wherein: the spacer and the gas cell are adjacent to each other in the main part; an electrically conductive film is formed on each of side surfaces of the spacer and the gas cell ; a bonding surface of the spacer and a bonding surface of the gas cell face each other; and a bonding pattern , that extends from the electrically conductive film , is formed on the bonding surface of the spacer , and a bonding pattern , that extends from the electrically conductive film , is formed on the bonding surface of the gas cell , and the bonding patterns that face each other are bonded by a bonding material ; such that the connecting terminals are respectively connected to pads formed on an insulating film through, at least, the electrically conductive films formed on the side surfaces of the spacer and the gas cell . the spacer and the gas cell are adjacent to each other in the main part; an electrically conductive film is formed on each of side surfaces of the spacer and the gas cell ; a bonding surface of the spacer and a bonding surface of the gas cell face each other; and a bonding pattern , that extends from the electrically conductive film , is formed on the bonding surface of the spacer , and a bonding pattern , that extends from the electrically conductive film , is formed on the bonding surface of the gas cell , and the bonding patterns that face each other are bonded by a bonding material ; such that the connecting terminals are respectively connected to pads formed on an insulating film through, at least, the electrically conductive films formed on the side surfaces of the spacer and the gas cell . <EOS>