The sonic soot blower includes a sonic wave oscillator that oscillates sonic waves by compressed air or steam, a frequency-regulating portion that varies the frequencies of the sonic waves oscillated by the above-described sonic wave oscillator, a resonance tube that resonates the oscillated sonic waves, and a horn that amplifies the same, wherein powdery dust adhered to members installed inside a boiler furnace, etc., are removed, and are prevented from adhering to the above-described members. The above-described frequency-regulating portion is a gas mixer which is connected to the upstream side of the sonic wave oscillator and is provided with two or more gas conducting flow channels for conducting a compressive gas whose temperatures and/or densities are different from each other, or a slide mechanism that varies the length of the above-described resonance tube. Since the sonic soot blower is able to oscillate sonic waves while regulating the oscillation frequency so as to be suited to the operating conditions of the boiler, it becomes possible to effectively remove ash from the heat transmission tubes and to effectively prevent the same from adhering thereto over a wide range of operating conditions of soot blower-installed equipment (such as a boiler).