To obvtain a pour point depressant which gives a very low pour point for a fuel oil or lubricating oil having a fixed crystallization temperature.

There is provided a pour point depressant for a fuel oil or lubricating oil whose the crystallization starting temperature (ta) and the crystallization finishing temperature (tb), as measured by a differential scanning calorimeter, satisfy the following formula (1): 20°C≥ta≥-40°C and formula (2): 5°C≥tb≥-70°C, wherein the pour point depressant comprises an alkyl (meth) acrylate polymer (A), and (Ta) and (Tb) of (A) satisfy the following formula (3): ta+20°C≥Ta≥ta-10°C and formula (4): tb+20°C≥Tb≥tb-10°C.