Hey @haejin! I came to steemit to gather more info about Bitcoin IRA! I actually set up my BTC IRA investment with https://www.401kcheckbook.com/ but wanted better info before committing more funds. I paid a low fee to get setup and pay a small - really small - fee for maintenance. It's virtually free. They use a novel structure that lets you set up an account at the exchanges to trade crypto in your IRA just as you do for yourself. You can check them it and let us know what you think.