This paper studies a time-fractional diffusion-wave equation with a linear source function. First, some stability results on parameters of the Mittag-Leffler functions are established. Then, we focus on studying the continuity of the solution of both the initial problem and the inverse initial value problems corresponding to the fractional-order in our main results. One of the difficulties encounteblack comes from estimating all constants independently of the fractional orders. Finally, we present some numerical results to confirm the effectiveness of our methods. 2020 Mathematics Subject Classification. 35R11, 35B65, 26A33. Key words and phrases. Initial value problem, inverse initial value problem, final value problem, time fractional wave equation, continuity/stability on fractional orders.We note that, for any > 0, there always exists C > 0 such that 1 − e −y ≤ C y for all y > 0. Therefore, we obtainCase 2. z ≥ 1. We see thatUsing the inequality 1 − e −y ≤ C y for any > 0 and y > 0, we obtainCombining the above cases completes the proof.CONTINUITY WITH RESPECT TO FRACTIONAL ORDER 777 Lemma 3.3. Let 1 < ν 0 < α < α < η 0 < 2 and > 0. Then there exists a positive constant D 2 (ν 0 , η 0 , , β, T ) such thatfor any 0 ≤ β ≤ 1 and 0 < t ≤ T .Proof. First, it is easy to see that