We have investigated charge and orbital (quadrupolar) ordering in perovskite manganites Pr1-xCaxMnO3 (x = 0.35, 0.40, 0.50) by ultrasonic measurements. Only transverse (C-11-C-12)/2 mode of the;-r, = 0.35, 0.40 and 0.50 compounds shows a softening from 400 K down to the charge ordering point T-co = 220 240 K. Tins softening is originated from the bilinear coupling of the quadrupole moment of the eg orbital in Mn3+ ion to the elastic strain. Furthermore, the elastic softening in both (C-11 = C-12)/2 and C-44 modes due to the coupling of the charge fluctuation mode to elastic strain is observed just above T-co, especially for the x = 0.50 compound. The considerable magnetic field dependence of the elastic constants is obseved. In particular, the magnetic fields up to 12 T releases completely the elastic softening of (C-11 - C-12)/2 mode due to the fact that the charge fluctuation is suppressed under 12 T in the = 0.40 compound.