The present invention provides a plastic optical component. The plastic optical component has superior characteristics including lightweightness, low cost and suitability for mass production. The plastic optical component exhibits superior moisture barrier quality while experiencing no uneven refractive index profile in their interior even if they are subjected to the effect of water in the environment. The plastic optical component has an optical component's body. A moisture-proof coating is directly or indirectly formed at least on surfaces of the optical component's body in contact with outside air. The moisture-proof coating is a multi-layered film including a lower inorganic layer and an upper organic layer. Sherwood number describing a water transfer process of the plastic optical component is in a range of 0.1 to 10, both inclusive.