Disclosed herein are a method, an apparatus and a storage medium for transform information encoding/decoding. A transform includes a primary transform and a secondary transform. A primary transform method and a secondary transform method are selected from among multiple different methods. A transform is performed on a target block based on a selected primary transform method and a selected secondary transform method. A primary transform method and a secondary transform method applied to the target block may be signaled using transform information such as a primary transform method index and a secondary transform method index.