Coun Alan Cullens, who is the Leader of the Opposition and Leader of Conservative Group at Chorley Council, is vacating his position on May 2.
Former Tory group leaders, Couns Mark Perks and Paul Leadbetter, are also not seeking re-election.
On that day, the people of Chorley will elect 15 new councillors across 15 wards.
Coun Cullens said: "I've had a promotion at work and will need to travel across the country, so it's not compatible.
"[The leadership] needs someone who can commit."
But the veteran councillor, who was previously in office from 2004 to 2012 before coming back in 2015, said this isn't the end of his career.
He said: "It's time out from politics, not total retirement!"
Regarding the Tory group's leadership, he added: "It's all down to the elections.
"We have our annual general meeting very soon after the elections.
"Once we know who's elected we can make a decision."
Coun Perks said: "After eight years as a councillor in Horwich and 17 years in Chorley, 25 years of my life serving communities my family now needs me more than ever.
"Within these years to say they have been eventful is an understatement - a decision to change careers; go back to college for four years; become a teacher; a M6 motorbike crash that left me in plaster for eight months and come through a lung embolism; a survivor of two strokes in 2015; become a carer for my mother who now has Alzheimer’s and still manage to continue to try my best helping others who contact me.
"It has been a honour and mainly enjoyable experience, met and got to know so many brilliant individuals in the community some who volunteer to make and do make a difference for so many. I’ve also met some individuals that I hopefully never ever meet again."
Coun Perks added: "As a councillor there have been successes, such as forming Astley and Buckshaw Juniors FC and Buckshaw Youth, when no one else wanted to fill a real need in the two communities.
"I have been proud to serve as the Mayor of both these super towns raising £20,000 as the Mayor of Chorley.
"It goes without saying to continue doing my very best serving the Clayton with Whittle division on Lancashire County Council until 2021."
In a statement on social media, Coun Paul Leadbetter said: "In May 2011 I was fortunate to be elected, as a Chorley Councillor for Chisnall Ward.
"I have tried, over the ensuing years, to serve the ward, and the Borough of Chorley, to the best of my abilities.
"I have, however, made the difficult decision that now is the time to stand down and let someone else have a go.
"I consider that being a Councillor is an honour and I hope that the person elected, on 2 May, will also do their best for the people, and place that they will have been elected to represent."
Polling offices in Chorley will be open from 7am to 10pm on May 2, with votes counted overnight.
To register to vote visit https://www.gov.uk/register-to-vote