Growth and disruption processes of dust aggregates by their mutual collisions play an important role in our understanding of planetesimal formation in protoplanetary disks. To examine the critical collision velocity of aggregate disruption, we performed numerical simulations of relatively high-velocity collisions of aggregates that consist of submicrometer-sized ice spheres. As an initial condition of aggregate structure in collision simulations, we used two kinds of aggregates. One is a relatively compact aggregate formed through ballistic particle-cluster aggregation (BPCA) and the other is a fluffy aggregate formed through ballistic cluster-cluster aggregation (BCCA). Our results show that icy aggregates are able to grow through collisions with velocities up to similar to 50 m s(-1), in spite of their initial structures and impact parameters. This supports a scenario of planetesimal formation through collisions of dust aggregates in protoplanetary disks.