Abstract: A scroll fluid machine is provided that includes: a fixed scroll; an orbiting scroll opposed to the fixed scroll, the orbiting scroll orbiting with a plurality of compression chambers formed between the orbiting scroll and the fixed scroll; a drive shaft driving the orbiting scroll; and a backside plate provided between the drive shaft and the orbiting scroll, an alignment hole being provided in each of the orbiting scroll and the backside plate, and an alignment pin for alignment and a seal member for sealing the compression chambers being provided in the alignment holes.