Supersymmetric extra U(1) models with a singlino dominated LSP

We investigate phenomenology related to the neutral fields in supersymmetric models with an extra U(1) derived from $E_6$. Our study is concentrated into the models which have a singlino dominated neutralino as the lightest superparticle (LSP). If such models satisfy a constraint for dark matter derived from the WMAP data, the lightest neutral Higgs scalar, a new neutral gauge field $Z^\prime$ and the LSP may be interesting targets for the study at the LHC. We also discuss features of the $Z^\prime$ in the models and its detectability at the LHC.