Honeycomb panel is widely used as flooring or wall material in various structures, e.g., buildings, aircraft, flooring members of railway car, and so on, due to high stiffness and lightness at present. Honeycomb panel, however, has a disadvantage that the adhesive used to glue honeycomb core and top plate may burn by fire. On the other hand, truss core panel has equivalent stiffness as honeycomb panel and is expected to be an alternative to honeycomb panel as it is safer for fire. To replace honeycomb panel with truss core panel, it is necessary to investigate the stiffness of truss core panel for bending, shear, compression, and so on. The bending case with a three-point bending model of truss core panel is chosen here. Four cases of analysis with/without work hardening effect and thickness change using two types of shell formulation are performed. These cases are compared with an equivalent honeycomb model. The study showed the effect of work hardening is very important to assess bending stiffness of truss core panel. It is also observed that the use of suitable shell formulation is necessary to obtain reliable result. In addition, the truss core panel shows bending stiffness comparable with conventional honeycomb panel.