SC相模原
After retirement, Nishigaya started coaching career at his alma mater University of Tsukuba in 2003. In 2004, he signed with Tokyo Verdy. He coached for youth team until 2009. In 2010, he became a manager for Meiji University. In 2012, he signed with Albirex Niigata and became a coach under manager Hisashi Kurosaki. However he resigned with Kurosaki in May. In 2013, he signed with Mito HollyHock and became a coach under manager Tetsuji Hashiratani. In June 2015, Hashiratani was sacked and Nishigaya became a new manager as Hashiratani successor. He managed the club until 2017. In 2018, he moved to SC Sagamihara and managed the club in 1 season.