Pulsating Heat Pipe (PHP) has been proposed as one of cooling techniques for electronic devices with innumerably increased heat flux. PHP can be classified into two groups, tubular PHP made by bending tube and Flat-Plate PHP (FP-PHP) which is channel-engraved plate. There have been many studies done on each type of PHP individually, but there is no study accomplished for comparing a flow and thermal characteristics of both types based on thermodynamics and hydrodynamics. The biggest difference between two kinds of PHP is the conduction through the plate in FP-PHP, while conduction in tubular type PHP is negligible. There are two main heat transfer paths in FP-PHP, conduction through the plate and heat transfer by rapid self-sustained oscillation of working fluid. However, the two heat transfer paths are not separated but interactive. In this study, experiment and its theoretical interpretation are performed for the conduction and its influence on heat transfer by working fluid. To visualize the fluid flow, High speed photography is applied. Base on experiment data and their interpretation, design of FP-PHP can be improved by adjusting conductive heat transfer.