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Photo- and electroproduction of $K\Sigma$ have been investigated near theirproduction thresholds by using an effective Lagrangian approach. For thispurpose, the background amplitude is constructed from suitable Feynmandiagrams, whereas the resonance terms are calculated by means of theBreit-Wigner form of multipoles. Experimental data available in the protonchannels ($K^+\Sigma^0$ and $K^0\Sigma^+$) with energies up to 50 MeV above thethresholds have been utilized to extract the unknown parameters. In theseproton channels the calculated observables fit nicely the experimental data,whereas in the neutron channels ($K^+\Sigma^-$ and $K^0\Sigma^0$) the predictedobservables contain some uncertainties due to the the uncertainties in thevalues of helicity photon couplings. To this end, new $K^0\Sigma^+$photoproduction data are urgently required. The present analysis indicates thevalidity of the $P_\Lambda = -\frac{1}{3} P_\Sigma$ relation derived a longtime ago. In the electroproduction sector the present analysis confirms thesmooth transition between photoproduction and low $Q^2$ electroproduction data.The effect of new Crystal Ball data is shown to be mild at the backward angles.It is also found that the electroproductions of $K^0\Sigma^+$ and $K^0\Sigma^0$are practically not the suitable reactions for investigating the $K^0$ chargeform factor, since the effect is small.

Electromagnetic production of $K\Sigma$ on the nucleon near threshold