To provide a developing device which is fast in forming time of a developing pattern corresponding to an image pattern and has a developing pattern of which surface state is stable, and to provide an image forming apparatus.

A developing pattern (version) which uses an ultrasonic curing agent is formed on a drum substrate 101 by applying an ultrasonic curing agent 102x on the drum substrate 101. The time it takes to form the developing pattern can be fast, since the time it takes to form the developing pattern (version) using the ultrasonic curing agent is about several seconds. Also since the ultrasonic curing agent has little deterioration with air, the developing pattern of a stable surface state can be obtained.