A serializer/deserializer (SerDe) is necessary to serialize a data object into a byte array and to deserialize in reverse direction. A SerDe that is used worldwide and runs quickly is the Protocol Buffer (ProtoBuf), which serializes a tree-structured data object into the Type-Length-Value (TLV) format. Acceleration of SerDe processing is beneficial because SerDes are used in various fields. This paper proposes a new method that accelerates the tree-to-TLV serialization through 2-way parallel processing called "parallelized serialization" and "parallelization with streaming". Experimental results show that parallelized serialization with 4 worker threads achieves a 1.97 fold shorter serialization time than when using a single worker thread, and the combination of 2-way parallel processing achieves a 2.11 fold shorter output time than that for ProtoBuf when 4 worker threads, File Output Stream and trees of 10,080 container nodes are used.