[Object] In manufacturing a GRIN lens by a sol-gel method, an operation for preparing a wet gel is facilitated and cracking in a base material during sintering and foaming during drawing are prevented.[Solution] The object is achieved by obtaining a GRIN lens by producing a wet gel from an alcohol solution containing a silicon alkoxide, a dopant alkoxide, and a boron alkoxide as the main ingredients, leaching the same, drying the same to form a dry gel, and sintering and drawing the same.