Northern Sea Route (NSR) shipping has recently gained the momentum for maritime trade between East Asia and Northwest Europe, taking the direct effect of reduced shipping distance of approximately 40% compared to the conventional Suez Canal Route (SCR) into account. Commercial NSR shipping of natural resources (e.g. gas condensate, natural gas and iron ore) has been increasing since 2010. Moreover, COSCO had achieved an experimental voyage of commercial container shipping in 2013 and 2015. Accordingly, many related studies have been accomplished for comparative analysis of estimated shipping cost through NSR and the alternative conventional routes. On the other hand, some 20,000TEU-class Ultra Large Container Ships (ULCSs) had started their SCR shipping operation on East Asia/Northwest Europe services since 2013, which had significantly improved their competitiveness over NSR/SCR-combined container shipping. This study aims at analyzing the effect of enlarging containerships on the competitiveness of the NSR/SCR-combined container shipping, referring to the rapidly changing external conditions.