This study aims to identify the similarities and differences between the Rules for the Transcription of Loanwords and the Orthography of the Korean Language. The Rules for the Transcription of Loanwords constitute a linguistic norm established separately from the Orthography of the Korean Language, and they serve as the standard for transcribing foreign words into Hangeul. While the Orthography of the Korean Language is based on the principle of writing standard Korean words phonetically in accordance with grammatical norms, loanwords do not fall under this category. Therefore, unlike native Korean words and Sino-Korean words, the Rules for the Transcription of Loanwords take loanwords as their object of transcription. In practice, however, the Rules for the Transcription of Loanwords deal with foreign words, and each phoneme of a foreign word serves as the source or starting point for its transcription. Thus, the Rules for the Transcription of Loanwords can be understood as a process that begins with the phonological form of a foreign word and generates a Korean lexical item categorized as a loanword. The Rules for the Transcription of Loanwords establish the principle of using only the 24 currently used Hangeul letters, yet in practice they reflect Korean phonological constraints by excluding complex consonant clusters and allowing only seven consonant letters in syllable-final position. This demonstrates that the Rules for the Transcription of Loanwords do not transcribe foreign phonemes directly, but rather convert foreign words into loanword forms that are phonetically realizable within the Korean phonological system. While the Rules for the Transcription of Loanwords are based on a transcriptional (phonemic) approach, language-specific provisions also include elements of a transliteration-based approach. In contrast to the Orthography of the Korean Language, which determines orthographic representation on a morphemic basis, the Rules for the Transcription of Loanwords determine representation on a phonemic basis. The Orthography of the Korean Language constructs orthographic forms by syllabically representing the phonological components of a single morpheme. The Rules for the Transcription of Loanwords, on the other hand, match Hangeul letters to the phonemes of foreign words and represent them syllabically. However, due to the constraints of Korean syllable structure, vowel letters are sometimes inserted to form permissible syllables. Because the Rules for the Transcription of Loanwords arrange letters at the syllabic level, they determine orthographic forms without regard to whether the coda of the preceding syllable and the onset of the following syllable can phonologically connect. The Orthography of the Korean Language determines the orthographic form of morphemes with grammatical considerations, and the actual pronunciation follows the Rules of Standard Pronunciation. Likewise, since the Rules for the Transcription of Loanwords assign one or more Hangeul letters to each phoneme of a foreign word, some orthographic forms inevitably violate Korean phonological constraints. Such forms, however, can be realized as appropriate surface forms in accordance with the provisions of the Rules of Standard Pronunciation.