A washing treatment apparatus and a washing treatment method are provided. A washing treatment apparatus washes in a washing container an object to be washed including a tubular portion, and a main body portion to which one end portion of the tubular portion is connected. The washing treatment apparatus includes a washing solution supply unit which pressurizes and supplies a washing solution to the washing container, a penetration hole portion which is provided on the washing container and includes a penetration hole into which the tubular portion can be inserted, an outlet hole portion which is provided on the washing container and includes an outlet hole through which the washing solution supplied into the washing container flows out to adjust pressure of the washing solution in the washing container to predetermined pressure.
