In vitro maturation of human oocytes is widely used for infertility treatment. However, the success rate of maturation varies depending on patients and molecular mechanisms underlying successful maturation remain unclear. Especially, gene expression profiles of oocytes at each maturation stage need to be revealed to understand the differential developmental abilities of oocytes. Here, we show transcriptomes of human oocytes during in vitro maturation by single cell RNA-seq analyses. Hundreds of transcripts dynamically altered their expression, and we identify molecular pathways and upstream regulators that may govern oocyte maturation. Furthermore, oocytes that are delayed in their maturation show distinct transcriptomes. Finally, we reveal genes whose transcripts are enriched in each maturation stage and that can be used for selecting an oocyte with a high developmental potential. Taken together, our work uncovers transcriptomic changes during human oocyte maturation and provides a molecular insight into the differential developmental potential of each oocyte.