Abstract: At least part of a processing liquid upward flowing in a storage space is split into a plurality of upflows and guided to a substrate held by a substrate holder. Many upflows are widely dispersed and formed in the processing liquid stored in the storage space, and the generation of downflows in the storage space is suppressed. As a result, bubbles are uniformly supplied to the substrate and substrate processing can be performed in high quality.

Abstract: To provide a bump stopper (1) having constricted parts (2A, 2B) in the circumferential surface and exhibiting buffering action by deforming resiliently when an annular distal end portion (3) collides against a partner member (61) in a state that a bump stopper central axis (0) is inclined to a collision surface (62), without sliding on the collision surface (62), thereby generation of noise being suppressed, the distal end portion (3) has a outside diameter and an inside diameter which expand toward the end, a diameter d1 at a collision start point (4) at the most distal end of the inner diameter surface is set substantially equal to or larger than the outside diameter d2 of the constricted part (2A) located just above it, and the distal end portion (3) deforms to tilt further to the outer diameter side through action of moment at the time of collision.

Abstract: To provide a bump stopper (1) having constricted parts (2A, 2B) in the circumferential surface and exhibiting buffering action by deforming resiliently when an annular distal end portion (3) collides against a partner member (61) in a state that a bump stopper central axis (0) is inclined to a collision surface (62), without sliding on the collision surface (62), thereby generation of noise being suppressed, the distal end portion (3) has a outside diameter and an inside diameter which expand toward the end, a diameter d1 at a collision start point (4) at the most distal end of the inner diameter surface is set substantially equal to or larger than the outside diameter d2 of the constricted part (2A) located just above it, and the distal end portion (3) deforms to tilt further to the outer diameter side through action of moment at the time of collision.