A syringe assembly constituting a prefilled syringe is provided with a cap. A cap body is configured to be displaced from a first position where a viewing portion is positioned in a cylindrical main body to a second position where the viewing portion protrudes in a distal end direction from an opening of the cylindrical main body. When a mounting tube portion of the cap removed from a syringe body is brought close to a nozzle portion of the syringe body, the cap body is pressed in the distal end direction by the nozzle portion, thereby being displaced from the first position to the second position, and the appearance of an outer peripheral portion of the viewing portion changes.
