We compute Picard groups of several nuclear and non-nuclear simple stably projectionless C * -algebras. In particular, the Picard group of the Razak-Jacelon algebra W 2 is isomorphic to a semidirect product of Out(W 2 ) with R × + . Moreover, for any separable simple nuclear stably projectionless C * -algebra with a finite dimensional lattice of densely defined lower semicontinuous traces, we show that Z-stability and strict comparison are equivalent. (This is essentially based on the result of Matui and Sato, and Kirchberg's central sequence algebras.) This shows if A is a separable simple nuclear stably projectionless C * -algebra with a unique tracial state (and no unbounded trace) and has strict comparison, the following sequence is exact: