The present disclosure describes a method capable of easily and rapidly inspecting the susceptibility of bacteria or fungi to an antimicrobial drug. The inspection method of the present disclosure is a method for inspecting susceptibility of bacteria or fungi to an antimicrobial drug using a micro-device having flow channels, including: incubating a mixture of the antimicrobial drug and a suspension to be inspected in the flow channels of the micro-device; and detecting bacteria or fungi derived from the suspension to be inspected in an observation area of the flow channels of the micro-device. The detecting step can be performed by detecting an increase or decrease in the number of or a change in shape of bacteria or fungi derived from the suspension to be inspected in the observation area by a microscope or the like.