To provide an inexpensive shoe insole which is simply deformed from a general shape into a shape adapted to an each user by heat and reduces waste disposal problems after using.

A shoe insole having thermal deformation performance is composed of a polylactic acid based resin having glass-transition point of 40-80°C. The above resin is formed into a general shape as a shoe insole, treated by thermal deformation under a temperature more than an ordinary glass-transition point and less than the forming temperature (for example, by immersion in hot water), and cooled to the temperature less than the glass-transition point (for example, by natural cooling 10 air), while holding the deformation shape, so as to fix the deformed shape. This constitution deforms the shoe insole 1 having a general shape by heat so as to provide the shoe insole 2 having a shape adapted to an each user.