STV has announced that its chief executive, Rob Woodward, is to step down after 10 years in the role.
The media group said Mr Woodward would stand down from his post and from the board within 12 months.
In a trading update, STV said it would "begin a process to identify a successor".
The announcement came a day after the group launched a new TV channel, featuring new programming including soap, drama and movies.
Mr Woodward said: "We have made a positive start to 2017 including the launch of new channel, STV2, and further commissions secured for STV Productions.
"As I confirm my decision to pursue fresh challenges after leading the company for the past 10 years, I am passionate about STV and its prospects to continue to deliver sustainable profitable growth for our shareholders.
"The company has an outstanding management team and committed and energised staff that will continue to build on the unique strategic strengths of the business."
Analysis: Douglas Fraser, BBC Scotland business/economy editor
It's one thing for a chief executive to leave in his own time and on his own terms (and much rarer if the boss is a she).
It's really rare to do so after taking on a company that was not expected to last as long as a decade without succumbing to structural change or hostile takeover.
STV Group chief executive Rob Woodward's approach to the job has appeared relaxed while very focussed. He stripped away the remaining parts of what had been Scottish Media Group.
The company has stopped harking back to its launch, 60 years ago, when Scottish Television was described by its founding chairman as as "a licence to print money".
It had to become less of a couthy institution.
STV Group chairwoman Margaret Ford said: "The board is indebted to Rob for his exceptional contribution to the turnaround of the group and his commitment and passion in driving positive growth over the past 10 years.
"He has built a strong legacy. With a first class leadership team and staff and highly engaged board in place, the company is well positioned to realise its future growth potential and continue to deliver to shareholders."
In its first-quarter update, STV said trading so far this year had been in line with expectations. National airtime revenues for the five months to the end of May are expected to be down by 8%, while regional airtime revenues are expected to be up 5%.
STV also said digital revenues continued to perform strongly, and were up by 11% in the first quarter.