Solution processing apparatus, solution processing method, and recording medium

The present invention provides a solution processing apparatus and a method thereof, which are capable of measuring a flow rate of a processing solution with a high accuracy in processing the substrate using the processing solution and monitoring the spray state of the processing solution. The solution processing apparatus comprises: a processing solution supply source (31), a flow path member, an ultrasonic flowmeter (40) mounted to the flow path member, and a solution transfer unit configured to transfer the processing solution to a nozzle (50), and mounted to the flow path member. The ultrasonic flowmeter (40) comprises paired piezoelectric elements (42) which are arranged on the periphery of the flow path member, and the operation of exciting ultrasonic wave by one piezoelectric element and detecting the excited ultrasonic wave by the other piezoelectric element is performed in two directions, therefore, it is possible to detect a minute flow rate of the processing solution in the tube being 1 mL/sec or less based on the time which starts from the exciting of the ultrasonic wave and ends with the detecting of the ultrasonic wave. In addition, the solution processing apparatus can monitor such as the spray states of bubbles in the processing solution and the processing solution based on the waveform change of the flow rate detected by the flowmeter.