A portable electronic apparatus includes a band to be mounted on a test subject. The band includes a plurality of fitting holes, a first surface as a surface facing to the test subject when mounted, and a second surface as a surface facing to an opposite side to the test subject when mounted, a contour line on the first surface side in a cross-section along a short-side direction of the band has a convex part. In the case of defining the surface corresponding to the second surface as a reference surface, and a position corresponding to the fitting hole in the first surface as a hole position, a height from the reference surface to the hole position is lower than a height from the reference surface to the convex part.
