To provide a washing apparatus capable of efficiently and effectively removing soils from objects to be washed.

A washing system 1 includes a washing tank 10 for storing fiber structure 100, a preparation tank 20 for agitating and mixing an additive 200 and a carbon dioxide of supercritical state or liquid state, and a valve 22, and a washing agent supply pipe 23 for supplying the washing tank 10 with the additive 200 and the carbon dioxide of supercritical state or liquid state which are agitated and mixed in the preparation tank 20.