Maybe you can help me: Why do want to know? Is it because you think that women should be pastors? Or is it because you want help in articulating the biblical case that there should not be women pastors?
Also, the burden of proof is not on those who believe that women should not be pastors. Rather, the burden of proof (onus probationis) is on those who favor woman pastors, since that is the innovation in the church after thousands of years otherwise (going back even to the Old Testament church). It is always the innovators who have to make their case.
Nonetheless, I can give you a few biblical reasons just briefly. Jesus appointed only male apostles, no women, even though there were women who had followed his ministry and witnessed his resurrection. Likewise, Christ's apostles Paul and Peter both explicitly state--in several passages--that it is not given to women to teach or have authority over men. And in the list of qualifications for a pastor, Paul talks about a pastor being "the husband of one wife," presuming there that the pastor will be a male.
It's something that has come up from time to time in my congregation. We have a woman as a pastor and the main argument is that not including women was a social custom of the time rather than religious doctrine.