To provide a device for treating adipose tissue and an apparatus for separating cell which smoothly discharge cell suspension while avoiding the decrease of recovery rate of fat-derived cells.

The device for treating adipose tissue 1 includes: a container 2 having an outlet 2a; a filter 3 which, in a container 2, covers the outlet 2a, partitions the inside of the container 2, catches the adipose tissue A, and passes fat-derived cells separated from the adipose tissue A; a valve V1 which opens and closes the outlet 2a; a pump 5 connected to the outlet 2a and sucking the inside of the container 2; injection means 8 which holds a solution C dissolving collagen and injects the solution C into a space partitioned by the filter 3 and including the outlet 2a; the pressure detection part 7, provided near the outlet 2a, and detects the pressure in the container 2; and a control unit 9 which controls the valve V1 and the injection means 8 based on the pressure detected by the pressure detection part 7 while liquid is discharged from the outlet 2a.