Dynamical coupled-channels study of photo- and electro-production reactions

A comprehensive study of the meson production reactions with initial $\pi N$, $\gamma N$, and $N(e,e')$ based on a dynamical coupled-channels approach is being made to explore the structure of the $N^\ast$ states in the Excited Baryon Analysis Center (EBAC) at Jefferson Lab. In this talk we present a current status of our study of the photo- and electro-production reactions, particularly focusing on the single and double pion production reactions. We will also discuss what impact the so-called ``complete-measurement'' of single pseudoscalar meson photoproduction reactions has on the construction of reaction models, which is a key to the precise determination of the N* properties.