Provided are: a method and a kit for transparentizing a biological specimen, which enable the transparentization within a short time and by which a wide variety of biological specimens can be transparentized； and a method and a kit for preserving a transparentized biological specimen. A method for producing a transparentized biological specimen, comprising steps as mentioned in items (A) to (C). (A) Step (1) of treating a material to be transparentized with a fixing solution that is an aqueous solution containing paraformaldehyde or the like, a nonionic surfactant (at a concentration of 1% or more) and an alkali and optionally containing a buffering agent to produce the material that is transparentized is involved. (B) Step (2) of treating the material that is produced in step (1) or a material to be transparentized which is produced by a conventional fixing method with a transparentization accelerator solution that is an aqueous solution containing a nonionic surfactant (at a concentration of 1% or more) and an alkali to produce the material that is transparentized is involved. (C) Step (3) of treating the material produced in step (1) or (2) with a preservation solution that is an aqueous solution containing a nonionic surfactant (at a concentration of 1% or more) and a polyhydric alcohol to produce the material that is transparentized is involved. A kit which can be used in the method.L'invention concerne : un procédé et une trousse pour rendre transparent un échantillon biologique, qui permettent de rendre transparent en une courte période de temps et par lesquels une large variété d'échantillons biologiques peuvent être rendus transparents； et un procédé et une trousse pour préserver un échantillon biologique rendu transparent. L'invention concerne un procédé de production d'un échantillon biologique rendu transparent, comprenant des étapes telles que mentionnées dans les objets (A) à (C). (A) Une étape (1) de traitement d'une matière à rendre transparente par
