ABSTRACT Heat source characteristics in the arc welding process such as temperature distribution of arc plasma, the current and heat input densities to the base metal is very important since they are one of the upstream factors of the process. Many studies have reported the distribution of temperature and metal vapour concentration in welding arc plasma by emission spectroscopy, and the distribution of heat input density to the base metal by split copper anode plate method. These studies generally require the axisymmetric assumption of the arc plasma. However, actual welding arcs are not limited as axisymmetric phenomenon. For example, tilted TIG arc welding is often performed due to the visibility and some reasons, resulting in a non-axisymmetric phenomenon in production sites. In order to measure such target, a tomographic approach is necessary. In this study, multidirectional measurement system with rotary split copper anodes was constructed to measure the non-axisymmetric distribution of the current and heat input densities of tilted TIG arc plasma. Integral values are measured from four directions and converted into a two-dimensional distribution by the image reconstruction method. It was experimentally revealed that as the tilting angle increases, the maximum value of current and heat input density decreases and the low density region of the distribution spreads towards the aiming direction. Although the measurement method using split anode including this study possesses the problem of arc deflection the insulating gap of split part, we found the fitting process on the measured data is useful to reduce this effect.