This study aimed to describe the affixes' forms, the functions, and the meanings found in the explanatory text of eighth grade students of SMP Negeri 4 Banyumas in the 2020/2021 academic year. This was a descriptive qualitative study. The data in this study were words with affixes in the explanatory text of grade VIII of SMP Negeri 4 Banyumas in the 2020/2021 academic year. The source of the data was the explanatory text of grade VIII students of SMP Negeri 4 Banyumas in the 2020/2021 academic year. The data collection in this study used observation non-participatory and note-taking techniques. Data analysis in this study used the distributional method of segmenting the immediate constituent technique (BUL). The results found 177 affixed words. The types of affixes found were in the form of prefixes (meN-, ber-, pen-, di-, ter-, and se-) as many as 66 data, infixes (-em-) which amounted to 1 data, suffixes (-an and its ) totaling 31 data, confixes (pen-/-an, per-/-an, per-/-i, ke-/-an, men-/-kan, men-/-ir, se-/-nya, ber-/-an, and men-/-i) which amounted to 58 data, and a combination of affixes (ber-/-an, men-/-kan, men-/-i, di-/-kan, di-/- i, per-, and per-/-i) totaling 21 data. Affixes with variations in the form are men-, ber-, pen-, ter-, pen-/-an, per-/-an, per-/-i, men-/-kan, men-/-ir, and meN-/-i. The functions of these affixes included forming transitive verbs, intransitive verbs, passive verbs, nouns, adjectives, numerals, adverbs, conjunctions, and no function. The meanings of these affixes were doing an action, producing mentioned by the basic forms, explaining passive action, describing past events, indicating collections, having no meaning, etc. The affixed words in the explanatory text were found in the form of verbs, nouns, and adjectives. Almost all of these words are found in sentences that describe natural phenomena. In addition, almost all of the sentences are structured as informative sentences but they contain explanations about natural phenomena.