Keywords:International Stratigraphic Chart, numerical age value, effective numerical value, astrophysical age, radiometric age
In July, 2018, ICS(International Stratigraphy Commission) of IUGS published the new International Stratigraphic Chart (ISC: v.2018/07). The author drew an attention to the public about some issues to be cautioned on the usage of numerical ages in the ISC based on the 2009 version(v.2009/08) at the JpGU before (Kaneoka, 2016). The essential points do not change between the two versions of ISC, but there are some differences in the representation of numerical ages in the new ISC. Here, the author comments some points about them and discuss issues of astrophysical and radiometric ages used in the ISC.