Ceramics are susceptible to cracking and poses a problem of lacking mechanical strength. Hence, the configuration in which the portion of the dielectric substrate having a thickness being thinner when being closer to the blowout outlet may have a staircase shape maintains mechanical strength.

A plasma discharge starting method according to the present invention is a plasma discharge starting method for a dielectric barrier plasma generator, the dielectric barrier plasma generator includes:

a dielectric substrate;

a high-voltage electrode provided on a first surface of the dielectric substrate;

a low-voltage electrode provided to face a second surface of the dielectric substrate;

a power introduction section provided at a first end of the high-voltage electrode;

a gas channel formed from a first end to a second end thereof between the dielectric substrate and the low-voltage electrode to allow gas to flow from the first end of the gas channel to the second end thereof; and

a blowout outlet formed at the second end of the gas channel to blow out the gas that has flown through the gas channel and the plasma that has been generated in the gas channel,

the dielectric substrate that includes a portion having a thickness being thinner when being closer to the blowout outlet,

the plasma discharge starting method includes:

a process A of introducing at least one type of starting gas selected from the group consisting of He, Ne, and Ar into the gas channel to generate plasma at a time of starting; and

a process B of introducing a gas for generating plasma into the gas channel after the process A.