Based on the hypothesis of lattice distortion, compositional complexity of high entropy alloys (HEAs) induces severe lattice distortion. Recent studies on the experimental and theoretical approaches to lattice distortion have been made to evaluate this hypothesis. However, the understanding of this effect is not complete due to their highly complex compositions and limited direct evidence. This work was designed to systematically study the effect of compositional complexity from unary to quinary compositions (Ni, FeNi, FeNiCo, FeNiCoCr and FeNiCoCrMn). To focus on the effect of interactions between constituent elements, the microstructural effect was minimized by controlling similar microstructural features such as grain size and residual strain. The micro lattice strain was evaluated on X-ray line profile analysis using the Williamson-Hall method and the local lattice strain was assessed by using pair distribution function (PDF) method through the total scattering data using the synchrotron X-ray diffraction measurement. Analysis on both the micro and local scales indicates that severe lattice distortion is not evident in FeNiCoCrMn HEA. Lattice strain and solid solution hardening are comparable between FeNiCoCrMn HEA and its sub-alloys. The high compositional complexity of FeNiCoCrMn HEA does not lead to a strong effect on lattice strain and solid solution hardening.