A method and apparatus for processing inter-RAT measurement in a dual modem device are disclosed. A method for processing inter-RAT measurement in a dual modem device includes receiving, by a first processor communicating with a first communication network, a measurement control signal including a parameter for signal measurement from the first communication network; transmitting, by the first processor, timing information based on a system frame number (SFN) and a global time to a second processor; acquiring time synchronization for the inter-RAT measurement between the first processor and the second processor on the basis of the system frame number (SFN) and the global time; transmitting the parameter from the first processor to the second processor; and measuring, by the second processor, a signal of a second communication network using the parameter.