  We construct flows on an amalgamated free product factor and characterize the
Rohlin property for them by freeness of $\mathbf{R}\times \mathbf{Z}$ actions
on a measured space. As a corolally, it turns out that there exist Rohlin flows
on an amalgamated free product factor. This shows that the classification
theorem of Masuda and Tomatsu for the Rohlin flows is also applicable to flows
on non-McDuff factors.
