PURPOSE: To obtain a polymer blend for packaging, etc., which is prepared from a polyolefin produced by low pressure synthesis, a copolymer of ethylene, carbon monoxide, etc., and a carboxylic acid salt of a specified element and has good properties including toughness, tear strength, transparency, elongation, and drawability.

CONSTITUTION: This photodegradable polymer blend is obtained by incorporating (A) 75-95 wt.% polyolefin produced by low pressure synthesis (example: high density polyethylene, etc.), (B) 5-25 wt.% copolymer of ethylene, carbon monoxide, and, as required, other polymerizable components which make the polymer blend contain 0.5-5 wt.% carbon monoxide, (C) 10-150 ppm carboxylic acid salt of an element of atomic number 22-58 (example: cerium 2-ethylhexanate, etc.).