Yes Jock Itch is very contagious and can spread from person to person through skin contact or through intercourse.
If you have jock itch you should avoid any skin contact with the other person until the Jock Itch has gone away and also avoid intercourse with a partner until the Jock Itch has gone away and you're no longer contagious.
You can help get rid of Jock Itch by applying some Apple Cider Vinegar to the Jock Itch since Apple Cider Vinegar is antibacterial and antiseptic as well which can kill off the bacteria that is causing the Jock itch.
Also wear loose fitting underwear or boxes and dry your pubic area really good after showering or bathing.