To provide a portable golf ball case having a heat insulator, capable of keeping the elastic force of a golf ball itself for increased carry of the golf ball, and also keeping the body of a golfer warm.

The interior of this portable golf ball case body 110 having a lid 120 is divided into at least two storing spaces 113a, 113b by a thin plate 112, a golf ball 50 is accommodated in the first storing space 113a, and a heat source 130 for performing heating required for holding the elastic force (flexibility) of the golf ball 50 is accommodated in the second storing space 113b.