Exploratory creativity (E-creativity) can be achieved by searching an area of conceptual space governed by specific rules. Existing studies on E-creativity mainly focus on how to use aspects of E-creativity to develop computational creativity tools, but E-creativity assessment scales have not been fully studied. To fill in the gap, this study developed an E-creativity assessment scale based on metrics and experimental determination studies. Eight indexes are promoted through literature investigation, which are related to E-creativity attributes, pre-requirement for the existence of E-creativity, relations between exploratory process and creativity, and results of E-creativity. Then, an empirical case study is applied to investigate the differences between nonprofessionals and professionals when using the developed scale. From the whole research, the results reveal that E-creativity is not simply related to the exploratory process and its concept space; instead, it is also related to the relations between the novelty of the exploratory process and the concept space of E-creativity. The results reflect the role of E-creativity in a creative process. This research provides a further understanding of E-creativity, which can contribute to further develop the definition of E-creativity. The E-creativity assessment scales can be used as a cue to further evaluate machine generated E-creativity.