The authors proposed a splice-type crack arrester for foam core sandwich panels. The splice-type arrester was intended to provide crack suppression functionality to a core-core splice of a foam core sandwich panel via the installation of carbon-fiber-reinforced plastic (CFRP) material between the two tapered cores and the replacement of sharp core edges with CFRP. The crack suppression ability of this type of arrester under mode II-type loading was investigated via a numerical analysis and an experimental evaluation. In the numerical analysis, the decreased energy release rate at the crack tip caused by this type of arrester was estimated quantitatively via a finite element (FE) analysis and crack closure integral. In the experimental evaluation, a load-displacement diagram obtained from a fracture toughness test showed that the critical load increased as the crack tip approached the leading edge of the arrester. The failure behavior indicated that the interfacial crack was completely suppressed near the leading edge of the arrester. A comparison of two different types of loading showed that the splice-type crack arrester had a greater crack suppression effect under mode I-type loading than under mode II-type loading, whereas the failure mechanisms were similar for both types of loading. Through this research, the interfacial crack suppression mechanism by the crack arrester was confirmed in the different loading conditions, i.e. the mode I type and mode II type. It can be said that this fact enhances the applicability of the crack arrester concept.