Disclosed is a drillship having a vortex suppression block with a recessed flow stabilizing part in a moon pool. The flow stabilizing section is formed so that a bottom of the vortex suppression block that protrudes from a bottom of a hull toward a stern in the moon pool is recessed in an upward direction of the hull to stabilize a flow in the moon pool and reduce a variation in resistance of the drillship. The flow stabilizing section (30) is formed by partly recessing the bottom of the vortex suppression block toward an upper portion of the hull. The drillship having this configuration provides resistance performance improvement and flow stabilization of the drillship.