Small, thin flat plates (called tabs hereafter) are attached to the upper and lower surfaces of a circular cylinder to control vortex shedding and reduce the mean drag and lift fluctuations at the Reynolds number of 100. We vary the location and size of the tabs and the distance between the adjacent tabs. The maximum amount of drag reduction by the tabs is 17%. It is found that the tabs perturb two-dimensional vortex shedding and introduce spanwise mismatch of vortex shedding, which weakens the strength of vortex shedding or even annihilates vortex shedding. The present result suggests that these tabs are an effective passive device for the control of vortex shedding behind two-dimensional bluff bodies.