For the secure transmission of information in the mobile wireless sensor network, the information between two nodes must be encrypted. To this end, nodes must share the common key necessary for encryption. At this time, the encryption algorithm should be symmetric cryptography rather than public-key cryptography in consideration of the process performance of sensor nodes, and the number of secret keys that each node must store and manage must be minimized in view of its memory capacity. In this paper, we propose a method of reducing the number of secret keys in spite of using the symmetric encryption algorithm. In this method, each node must store and manage by assigning a unique ID to it, and by ensuring that only those two nodes whose the Hamming Distance between their IDs is " 1" share the same secret key. According to this method, each node needs to store and manage only log2N symmetric secret keys so that two nodes participating in the mobile wireless sensor network can obtain a common key for secure transmission of information. In this paper, we also propose the protocol and algorithm for obtaining a common key between two nodes using their own secret keys and the secret keys acquired from their neighbor nodes, and evaluate the performance (including node connectivity, network resilience against node capture, memory capacity, and key pool size) of our proposing method.