To make it possible to manufacture a highly durable and highly photochromic characteristic photochromic lens at low cost by a method wherein a photochromic substance, which is adhered to the surface of a plastic lens base material by a vacuum spraying method, is heated so as to be infiltrated in the surface of the base material.

A photochromic substance is adhered to the surface of a plastic lens base material. After that, the photocromic substance is infiltrated from the surface of the plastic lens base material towards the direction of the thickness in the region of the range of about 0.1-100 μm. The preferable adhesion of the photochromic substance to the base material of the photochromic substance is a dry system method such as a vacuum spraying method, a spatter spraying method or the like. When the vacuum spraying method is employed, normally, its degree of evacuation is set to be 5×105 Torr or less. When the plastic lens base material adhered with the photochromic substance is heat- treated, the photochromic substance is infiltrated in the surface of the plastic lens base material, resulting in manufacturing the plastic lens with a desired photochromism.