^<35>Cl NQR frequency in 4,4'-dichlorobenzophenone was observed as a function of temperature. It was revealed that there exist three modifications in the range of 77 K to 420 K. The first-order phase changes were found to occur at 186 K and 180 K. The Zeeman effect on the ^<35>Cl resonance line in the high-temperature phase was examined at room temperature by using a single crystal. The molecular shape was deduced on the basis of the axes of the electric field gradients.