In order to study quantum measurement theory, sequential product defined by A • B = A 1/2 BA 1/2 for any two quantum effects A, B is introduced. Physically motivated conditions ask the sequential product to be continuous with respect to the strong operator topology. In this paper, we study the continuity problems of the sequential product A • B = A 1/2 BA 1/2 with respect to the other important topologies, as norm topology, weak operator topology, order topology, interval topology, etc.