A polymer film has an average film thickness T0 along a straight line D passing through the center of gravity of a two-dimensional projection such that the area of the polymer film is maximized, satisfies equation (a), the average value L of distances 1 from the center of gravity to edges satisfies equation (b), the Young's modulus E satisfies equation (c), and the thickness deviation Δ defined by equation (d) satisfies equation (e); and a dispersion liquid and an agglomerate using the same. (a) 10 nm≤T0≤1000 nm, (b) 0.1 μm≤L≤500 μm, (c) 0.01 GPa≤E≤4.3 GPa, (d) Δ=1−T1/T2, (e) 0.346E×10−9−1.499