ULTRASONIC CLEANING METHOD AND APPARATUS

There is provided an ultrasonic cleaning method capable of reliably cleaning to remove adhesive components even when the adhesive components adhere to a rigid substrate. The ultrasonic cleaning method comprises performing the following steps (1) to (5), in this order: (1) a step of immersing a rigid substrate having an adhesive adhering to a surface thereof in an aromatic alcohol-based cleaning liquid at 25 to 60°C; (2) a step of cleaning off the adhesive on the rigid substrate by ultrasonic oscillation while keeping the state where the rigid substrate is immersed in the step (1); (3) a step of subsequently immersing the rigid substrate in a glycol ether-based cleaning liquid at 25 to 60°C; (4) a step of rinsing off the aromatic alcohol-based cleaning liquid adhering to the rigid substrate by ultrasonic oscillation while keeping the state where the rigid substrate is immersed in the step (3); and (5) a step of subsequently rinsing off the glycol ether-based cleaning liquid and aromatic alcohol-based cleaning