3D-printed carbon fiber reinforced plastic (CFRP) composites have attracted significant attention due to their design flexibility and low manufacturing cost. However, 3D-printed CFRP contains inherent defects that occur during the manufacturing process. As the manufacturing defects are likely to degrade the mechanical performance of the 3D-printed CFRP, these defects require extensive investigation. Typically, x-ray micro-computed tomography (micro-CT) is used to detect manufacturing defects, but as micro-CT cannot be applied to large structures, the laser ultrasonic testing (LUT) method has been proposed. In this study, two specimens with different stacking sequences were manufactured using a continuous fiber 3D printer. The two specimens were then inspected using LUT and micro-CT. The manufacturing defects were successfully visualized using LUT, and similar defects were detected in the micro-CT inspection results. The size, location, and shape of the detected defects were evaluated by comparing the LUT and micro-CT inspection results. Consequently, the LUT method showed a performance comparable to that of micro-CT for detecting the manufacturing defects of 3D-printed CFRP. Since the LUT is capable of inspecting large scale 3D-printed composites, it will be absolutely advantageous in real world applications.