The sudden departure of Pidgeon, who was formerly managing director of clothing chain Bonmarche, followed that of development director Julie Cook at the end of August, although Cook remains as a consultant.
Moss Bros said that chief executive Philip Mountford had 'taken direct control of Moss, overseeing operations and buying'.
When Pidgeon joined Moss Bros in April, Mountford said: 'This appointment will enable the company to focus on its strategy of substantial growth over the next three to five years. David will be paramount to the delivery of profitable results within what remains a challenging retail environment.'
A spokeswoman declined to comment further on the reasons for his departure after only six months.
Moss Bros also announced the appointment of Michael Hitchcock as group finance director after Roddy Murray left at the beginning of this year.
Hitchcock - who will take up his post from October 11 - was former finance director of Ottakar's.