Two-dimensional magnetohydrodynamic plasmas are believed to obey a power-la
w behavior in terms of the size ilk of an eddy. The scaling law under a ran
dom Gaussian stirring force is studied through the field-theoretical renorm
alization-group (RG) method. In the process, a generating functional is con
structed, and from power counting, the primitively divergent vertex functio
ns are identified. These divergent functions are regularized by proper reno
rmalizations of the viscosity, the resistivity, and the size of the fluctua
tion and by invoking the Ward identities resulting from the Galilean invari
ance. The fixed point of the RG equation is found, and the scaling solution
s of the energy spectra are obtained in terms of the noise power spectrum.