The 31-year-old, who took over from Sir Alastair Cook in 2017, holds the record for most matches and victories as England captain.
But the Yorkshireman also holds the record for most losses, while being in charge of the team after a sad race in which he has since won only one of their last 17 Tests.
England fell to a 10-wicket defeat in the series decision against the West Indies in March, following a 4-0 Ashes defeat in Australia over the winter.
Root said: ‘After returning from the Caribbean tour and having time to reflect, I have decided to step down as England’s Test captain.
‘It’s been the most challenging decision I’ve had to make in my career, but after discussing this with my family and my loved ones; I know the timing is right.
‘I’m immensely proud to have been captain of my country and will look back on the last five years with immense pride. It has been an honor to have done the job and to have been a guardian of what is the pinnacle of English cricket. ‘
Former English captains Michael Vaughan, Nasser Hussain and Michael Atherton were among those demanding Root be replaced after the Caribbean tour.
Root added: ‘I have loved leading my country, but recently it has hit home how much it has taken on me and what impact it has had on me away from the game.
‘I’m excited to continue to represent the three Lions and produce performances that will enable the team to succeed. I look forward to helping the next captain, my teammates and coaches in the way I can. ‘
While England’s performance declined towards the end of Roots’ tenure, he remained one of the most productive running scorers in the world throughout his captaincy and is already the country’s second highest Test running scorer behind Cook.
Root scored 14 centuries as a skipper, with his figure of 5,295 running the highest of any English captain and the fifth best ever.
England and Wales Cricket Board CEO Tom Harrison said: ‘Joe has been a unique role model during his tenure, balancing the requirements for the Test captain while continuing to shine brilliantly through his own personal achievements.
‘It has been a privilege and a great pleasure to have worked with him in his capacity as our Test captain and I know he will continue to drive English cricket forward as a senior player and offer his wealth of experience and advice to support his successor. ‘
Root led England to a 4-1 series win over India in 2018 and a 3-1 win over South Africa in early 2020. Under his captain, England won two away series in Sri Lanka.
His notable league losses include two heavy Ashes defeats in Australia, in 2017-18 and 2021-22. England were also beaten at home by New Zealand last summer.
The ECB has not confirmed who will replace Root, but vice-captain Ben Stokes and veteran-tempo bowler Stuart Broad are two of the more realistic options.
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