An impact detector includes a case, an impact indicator disposed on a front side of the case, to indicate an impact history of the impact detector, a first weight that moves inside the case to a side to which the case falls, causing the impact indicator to indicate the impact history by moving through at least one of a first transition path and a second transition path, a first guide member to guide the first weight to a first impact detection position along the first transition path when the case falls in a first direction, and a second guide member to guide the first weight to the second impact detection position along the second transition path when the case falls in a second direction. The first transition path at least partly overlaps with the second transition path on a projection plane on the front side of the case.