The arches of my feet get sore when I jump rope? Why is that?

Lack of support. This is usually caused by shoes that do not fit properly or have poor arch support that will cause a strain of the plantar fasciia, which is a ligament that covers and protects the bottom of your foot. See your podiatrist for orthotics and examination.
Foot type? Are you barefoot? Or wearing sneakers? You might be straining your arch. With certain foot types this can be increased i.E a flatfoot where one is jumping up and down with full body weight for example will excessively strain the arch. This will cause soreness. Make sure you have good arch support.

Related Questions

How come when I jump rope the arches of my feet get sore after a couple minutes?

Likely. They need support. Wear an orthotic or arch support when performing this excercise next time. Read more...
Lack of support. If you have a flexible arch or flat foot position or old and worn out shoes, this will cause excessive movement in the middle arch area of your feet that will cause ligament movement to the joints and bones and create teh sore arches. Try either taping your feet or getting a more stable shoe. Avoid a very flexible shoe and don't jump barefoot. Read more...