John Robertson is taking a period of compassionate leave after a family bereavement, Inverness have announced.
Robertson, 56, is in his second spell at Caley Thistle and chief executive Scot Gardiner described the manager as "an exceptional coach".
Inverness are eighth in the Scottish Championship with four games in hand.
"John has done extraordinary work behind the scenes under the most difficult circumstances," said Gardiner.
"Particularly following the serious illness which struck down his assistant manager Scott Kellacher at the turn of the year.
"While Scott continues to make good progress away from the club, John has now suffered a bereavement in the saddest of circumstances.
"We believe that given those circumstances that it is best he takes some time away from the club to gather his strength. John is our friend and colleague, and he is an exceptional coach."
Scotland international striker Robertson has also managed former club Hearts as well as Ross County, Livingston, Derry City and East Fife after his first spell at Inverness ended in 2004.