1. An asset managing apparatus, comprising: a recording unit including a first database for recording an entity identifier indicating a plurality of assets made to correspond to each of a plurality of users by relating the entity identifier to layer information used by each of the plurality of users, the layer information indicating each of a transaction layer that is a layer associated with an asset relating to a service, an application layer that is a layer associated with an asset relating to virtual software, a virtual infrastructure layer that is a layer associated with an asset relating to the virtual hardware, and a physical infrastructure layer that is a layer associated with an asset relating to real hardware and real software, and a second database for recording the entity identifier by relating the entity identifier to a linking identifier indicating a relationship among the plurality of assets; a search extent setting unit, including a processor, configured to identify a layer made to correspond to the first asset when the first asset is related to a first user of the users is designated by referencing the first database by using the entity identifier of the first asset, to set all layers to a search extent when the identified layer is the physical infrastructure layer, and to set the layers other than the physical infrastructure layer to the search extent when the identified layer is other than the physical infrastructure layer; and an extracting unit configured to reference to the first database and the second database by using the first asset in the search extent set by the search extent setting unit and to extract another asset related to the first asset but not related to one of the plurality of assets corresponding to one of the plurality of users other than the first user, including extracting, from among assets of the transaction layer, the application layer and the virtual infrastructure layer, all other assets directly or indirectly using an output of the first asset, all input assets that are the other assets directly or indirectly used by the first asset as an input, all the other assets that use the input asset as an input and are different from the first asset, and all the other assets directly used by the input asset present in the transaction layer, the application layer and the virtual infrastructure layer as an input from among assets of the physical infrastructure layer.