By use of synchrotron radiation we have studied X-ray diffraction of LnSb(Ln=lanthanide) with a NaCl-type structure up to 35 GPa at room temperature. Pressure-induced phase transitions of LnSb were found at room temperature. The phase transition with a crystallographic change occur at around 13 GPa for PrSb and 24 GPa for LuSb. The high-pressure phase of LnSb is classified into three groups. The lighrer LnSb(Ln=La, Ce, Pr and Nd) have a tetragonal structure (distorted CsCl-type) at high pressures. The structure of the high pressure phase of middle LnSb(Ln=Sm, Gd and Tb)is unknown. The heavier LnSb(Ln=Dy, Ho, Ef, Tm, Lu and Y) have a CsCl-type structure at high pressures. The high-pressure structural behavior of LnSb is discussed. We have obtained the bulk moduli of LnSb with the NaCl-type structure.