Jun Ideguchi (井手口 純, Ideguchi Jun, born May 14, 1979) is a former Japanese football player.

Ideguchi was born in Toshima, Tokyo on May 14, 1979. After graduating from high school, he joined the Yokohama Marinos (later Yokohama F. Marinos) in 1998. Although he played for the club until 2002, he did not play as much as Japan national team defenders Masami Ihara, Norio Omura, and Naoki Matsuda. He also played for Consadole Sapporo (1999), Shonan Bellmare (2001), and Sanfrecce Hiroshima (2002). In 2003, he moved to Sagan Tosu. He played many matches at Sagan. He moved to Tokushima Vortis in 2006. He retired at the end of the 2006 season.

In August 1995, Ideguchi was selected Japan U-17 national team for 1995 U-17 World Championship, but he did not play in the match.