With the rapid development of information and communication technology in recent years, the informatization of society is unstoppable. One of the fundamental technologies in this information society is cryptography. Cryptography is now an indispensable technology for the secure use of the Internet and for maintaining the confidentiality of electronic data. Among the cryptographic techniques, Salsa20, a stream cipher, is the predecessor of ChaCha20, which was selected for TLS 1.3, and its security analysis is an important issue. In Salsa20, differential analysis and Diffusion analysis, which use the bias between specific input and output differences, are proposed. In this study, we focus on the input/output differences of Salsa20 and experimentally find a new linear bias for multiple input differences and output difference.