A lens blocking/deblocking method/device to adhere an ophthalmic lens to a lens holding block A method for blocking an optical lens component (100) on holding unit (200) having bottom part (230) inserted and fixed in lens machining tool (400) and an upper part (250) having upper assembling surface (210) and external side parts (241). The method provides the optical lens component (100) with layer (320) of one-side adhesive tape arranged on bottom of component (100) to cover at least partially bottom (120); (S20) providing thermoplastic material on upper assembling surface (210). The thermoplastic material is heated where a part thereof flows under moderate pressure; (S30) placing the optical lens (100) with layer (320) on thermoplastic material when the thermoplastic is softened; (S40) applying pushing force (P1) on the optical lens (100), to spread the thermoplastic between layer (320) and upper assembling surface (210) and covers external side parts (241).