To provide a portable weight measuring instrument capable of confirming whether the weight of a suitcase is equal to or greater than a regulated value even without power of electricity or the like.

A portable weight measuring instrument is miniaturized by putting a spring for sensing weight in an upper box for supporting an object to be measured and in a lower box for lifting the object to be measured and the upper box. The portable weight measuring instrument includes a spring 4 for converting a vertical load into a horizontal extension, a top face located at the top of the spring to receive the load of the object to be measured, a body 1 in the shape of a box having an opened bottom corresponding to an opposite face of the top face, a grip part 3 located under the spring to transfer the vertical load when lifting the object to be measured and the entire body to the spring, and a notification part 5 for visually or auditorily notifying a measurer of the weight by the extension of the spring.