A double-integration signal processing apparatus for pulse width amplification and A/D conversion is provided. The current mode double-integration conversion apparatus includes: a current mode double-integration unit which integrates an input current in a predetermined time interval and outputs an integration voltage; a comparison unit which compares the integration voltage output from the current mode double-integration unit with a predetermined comparison voltage V k and outputs an comparison pulse signal; and a gate logic unit which performs a logic operation by using the comparison pulse signal of the comparison unit and an internal signal and outputs an logic operation pulse signal. Accordingly, the current mode double-integration conversion apparatus can be applied to various sensors.