Material extrusion (ME)-type printing is the most popular among the 3D printing processes. In this study, the cross-section morphology of an ME-type 3D printing manufactured specimen was observed and the relationship between cross-section morphology and deposition strength was analyzed. Cross-section morphologies were also observed according to the thermal property of material. Thermal conductivity of material was involved during the cooling and frozen process of layers and subsequently it strongly influenced on the cross-section morphology and the surface roughness.