A proliferation promoting agent for neural stem cells, which comprises a compound produced by Penicillium sp. CND1007 (FERM BP-10917) or a pharmaceutically acceptable salt thereof, as an active ingredient; a novel compound produced by Penicillium sp. CND1007 or a pharmaceutically acceptable salt thereof; a method for producing neural stem cells, which comprises culturing a neural stem cells to proliferate the neural stem cells in a presence of the compound produced by Penicillium sp. CND1007 or a pharmaceutically acceptable salt thereof, and harvesting the neural stem cells from the culture; and the like are provided.