An inspection apparatus inspects a package group including a plurality of discrete packages that are successively connected in a chain. The inspection apparatus includes an irradiating component, a light receiving component, a generating component, an identifying component, an estimating component and a weight diagnosing component. The irradiating component is configured and arranged to irradiate inspection waves to the package group with the inspection waves being X-rays or terahertz waves. The identifying component is configured to identify a plurality of discrete package regions corresponding to the discrete packages from an inspection image generated by the generating component. The estimating component is configured to estimate one or more weight values respectively corresponding to one or more of the discrete package regions. The weight diagnosing component is configured to diagnose the package group as being abnormal in weight when any of the weight values falls outside a predetermined range.