Morchella (morel) includes prized edible and medical mushrooms in the world. Since 2012, commercial cultivation of morels in the field has developed rapidly in China. However, coupled with the rapid expansion of morel cultivation, diseases have been become serious threats to morel production. White mold is one of the most serious diseases on cultivated morels. The present study aimed to confirm this pathogen by following Koch's postulates, and to identify it using molecular evidence. Our results indicated that healthy Morchella fruiting bodies inoculated with Paecilomyces sp. isolates produced typical white mold symptoms, and the internal transcribed spacer (ITS) sequences of the Paecilomyces sp. were 99% similar to that recovered from an epitype of Paecilomyces penicillatus. Therefore, P. penicillatus was considered to be the causative agent of white mold. White mold occurred from the initial harvest to the storage and preservation process, and it produced white mold-like symptoms on the caps and stipes of Morchella. This is the first time that white mold has been reported on cultivated Morchella.