To digest a living body tissue effectively, while maintaining the soundness of cells.

A device 1 for decomposing the living body tissue is provided by equipping a container 2 for storing the living body tissue A and digestive enzyme liquid B, and a rocking mechanism 3 for rocking the container 2 about a horizontal axis line, and rocking the container within 15 to 50 angular range and in 5 to 40 cycles/min rocking speed by the rocking mechanism 3.