A developer stirring unit, a developing device containing the developer stirring unit and an image forming apparatus comprising the developing device are supplied capable of correctly judging a remainder amount of developer in accommodating tank. The housing has a front wall, a rear wall and opposing side walls disposed transverse to and between said front and rear walls. The intermediate range has a transition point having a sound level higher than the first level but lower than the second level. The lock member has at least one rod extending therefrom, the at least one rod being configured to releasably engage with the at least one aperture. A pitch composition is obtained which can be made into particles and transported without sticking together.