To provide an imaging apparatus capable of reducing unusable state in the case a memory area is in the near-full state, and a controlling method therefor.

Whether or not a memory area (HDD, SRAM, or the like) is in the near-full state is judged (step S1). In the case the memory area has a standard value or less, the memory area is judged to be near-full (step S1/yes) so that a message such as 'due to the memory shortage, it is set to be ACSOFF' is displayed in an operation display unit 2 as well as the ACS (color image automatic judgment) function is switched off for setting a black and white mode (step S2). In the case the memory area is judged to have a sufficient vacant area in the step S1 (step S1/No), the ACS mode is set (step S3). Therefore, according to this apparatus, since a specific mode for automatically switching off the ACS function in the case the memory area is in the near-full state is provided, the unusable cases can be reduced dramatically.