The Young鈥檚 modulus of graphene is estimated by measuring the strain applied by a pressure difference across graphene membranes using Raman spectroscopy. The strain induced on pressurized graphene balloons can be estimated directly from the peak shift of the Raman G band. By comparing the measured strain with numerical simulation, we obtained the Young鈥檚 modulus of graphene. The estimated Young鈥檚 modulus values of single- and bilayer graphene are 2.4 卤 0.4 and 2.0 卤 0.5 TPa, respectively.