These days we come across many wicked problems whose solutions are beyond individuals intellectual ability. These problems can be resolved through collaborative group interaction. We developed an internet-based asynchronous group interaction support system, after looking into the collaborative problem solving process and the IBIS (Issue-Based Information System) argumentation model. It has the following characteristics ; 1) it is developed based on the modified IBIS model which is a model for group interaction to resolve wicked problems ; 2) it supports both processes of seeking and comparing solutions, while most similar systems do not have a feature to support the latter process ; 3) different structures can be defined dynamically according to the purpose of group interaction, so that it could be used for collaborative problem solving in a specific domain. To show the usability of the system, we carried out an experiment, whose result is shown at the end.