The present study investigated if the argument-driven inquiry (ADI) model with embedded explicit-reflective teaching of NOSI improved pre-service science teachers' (PSTs) comprehension of the nature of scientific inquiry (NOSI). The study employed the qualitative experiment method with 16 PSTs. The PSTs working in small groups conducted seven ADI laboratory activities. During the activities, NOSI aspects were made explicit, and reflective discussions were conducted to provide the PSTs with opportunities to discuss and deepen their understanding of NOSI. A Views About Scientific Inquiry questionnaire and follow-up interview were applied to understand participants' understandings about NOSI before and after the instruction. The PSTs displayed a promising understanding about NOSI before the instruction. Some of the PSTs already had informed views on some NOSI aspects before the instruction, and "inquiry process is instructed by the question" was the most well-known aspect of NOSI. After the instruction, the PSTs developed their views on almost every aspect of NOSI. The most well-understood aspects of NOSI were that "scientific research all starts with a question" and "no single scientific method." The results provided evidence that the PSTs performed significantly better after the ADI laboratory instruction with embedded explicit-reflective teaching of NOSI.