Philautus jacobsoni is a species of frog in the Rhacophoridae family. It is endemic to Central Java, Indonesia. Philautus jacobsoni van Kampen has discovered by van Kampen in 1912. Since the first discovery of this species, there is no next discovery. While Philautus jacobsoni researchs still rarely. Philautus jacobsoni van Kampen is listed as Critically Endangered (IUCN 2004) because there is continuing decline in extends and quality of its habitat on Mount Ungaran, Central Java. In March until June 2010, we held exploration for amphibian inventory at Banyuwindu forest (north of Ungaran Mountain) and we fund some species and one of them is a Philautus sp. And the picture was taken. We fund it at coffee tree. We hope it can be a clue that Philautus sp still survive at their habitat. It may be possible that Philautus jacobsoni is still survive at Ungaran Mountain because there is too many areas that never been surveyed. The aim of this research is to investigate Philautus jacobsoni existence in Ungaran mountain area. There are few reference explain that it is unavailable. There are two probabilities, first, this species is extinct actually and second, cause there is no further research about this species. Major threats of this species and the other frog species at Ungaran Mountain are conversion area activity become tea and coffee plantation. At January 27th 2004, in Banyuwindu had been ever a flod and land slide at the west of Ungaran mountainside because forest destroyed. Then forest fire was happened at east of Ungaran mountainside. From this explain, one thing is sure that disasters cause Philautus jacobsoni ’s habitat decline.