Mr Anek said the 106-year-old statue is in a state of disrepair, damaged by dust, vehicle exhaust fumes, smokes from incense sticks and candles, rain, sun and carbon pollution.
It has been over 20 years since it was last renovated, he said.
The Fine Arts Department will clean up the statue, make needed repairs and improve its surroundings, plants decoration and illumination.
The wok was expected to take two months and be completed by the end of June.
Although scaffolding would be erected around the statue, people could still pay homage to King Rama 5 as usual.
After the renovation, there would be a special zone designated for worshippers to lay down their offerings.
Details of the planned renovation can be seen at the department's website www.finearts.co,th, Mr Anek said.