This paper presents a design procedure of a bus bar embedded Rogowski coil in a laminated bus bar from the viewpoint of geometry. The current sensor can detect a current waveform inside the laminated bus bar. The characteristics of the current sensor depend on the both the coil and the laminated bus bar geometry; therefore, the impact of the coil geometry should be discussed. This is achieved using a electromagnetic field simulation. The frequency bandwidth of the sensor is limited by the stray components induced by the geometry. Further, the post processing method is needed to improve the frequency bandwidth of the current sensor. The performance of the current sensor is validated experimentally in a buck converter circuit through comparison with a conventional measurement method.