The uncertainty of the boundary shape is a major source of spurious artefacts in electrical impedance tomography (EIT), as it can be one of the major causes of the error in the measured voltages. In this study we show that even a very small change on the boundary can create artefacts on EIT images depending on the conductivity contrast. The external boundary can be parameterised by the coordinate data of the position of the electrodes. This is a suitable way to parameterise the boundary shape, as the positions of the electrodes are the most sensitive area on the boundary. The aim of this paper is to reconstruct the position of the electrodes and the conductivity image simultaneously. The issues related to the error in the positions of the electrodes are discussed. In a numerical example we show simultaneous reconstruction of the internal conductivity map and the position of the electrodes.