Provided are a portable radiographic image detector capable of transmitting with a smaller number of transmissions the read results of dark reads performed a plurality of times when an offset calibration or the like is carried out, and a radiographic image generation system using the portable radiographic image detector. The portable radiographic image detector (1) comprises: a sensor panel (4) in which a plurality of radiation detector elements (x, y) are disposed in a two-dimensional shape a storage means (7) for storing dark read values (Dk (x, y)) outputted from the radiation detector elements (x, y) under the condition that radiation is not irradiated a calculation means (6) for calculating the offset correction value (O (x, y)) for each of the radiation detector elements (x, y), based on a plurality of dark read values (Dk (x, y)) obtained from the outputs of the radiation detector elements (x, y) at every dark read of a plurality of times of dark reads performed in advance a communication means (3, 13) for transmitting the offset correction value (O(x, y)) for each of the radiation detector elements (x, y) to an external device and a built-in battery.
