To provide a treatment solution-spraying nozzle of a substrate treatment apparatus capable of providing sufficient ultrasonic wave vibration to a treatment solution by preventing accumulation of foams in the treatment solution-spraying nozzle and capable of preventing damages on an ultrasonic oscillator.

This treatment solution-spraying nozzle 1 is provided with a nozzle main body 43 comprising a treatment solution storing part 42 for temporarily storing a treatment solution and a treatment solution discharging outlet 47 formed under the treatment solution storing part 42, an ultrasonic oscillator 41 for providing ultrasonic wave vibration to the treatment solution in the treatment solution storing part 42, a head providing part 45 for applying pressure to the treatment solution in the treatment solution storing part 42 due to formation of a smaller opening part 46 than the treatment solution discharging outlet 47, and a foam discharging hole 44 formed in the ultrasonic oscillator 41 for discharging foams existing in the treatment solution storing part 42 to the outside of the treatment solution storing part 42.