A manufacturing method of a high-reliability hermetic container includes an assembling step of arranging, between first and second glass substrates, a sealing material including first and second straight line portions stretching in different directions and a coupling portion connecting these straight line portions, with a viscosity of the sealing material having a negative temperature coefficient, and a scanning sealing step of performing scanning to the first straight line portion and the coupling portion while irradiating local heating light at least once. Scanning to the second straight line portion and the coupling portion is performed while irradiating the local heating light at least once, and the assembling step further forms at least a part of the sealing material at the coupling portion with a film thickness thinner than the sealing material in a region adjacent to the coupling portion of the first straight line portion.