A synchronization apparatus for synchronizing an operation of a first processing unit configured to perform a pre-processing on an input signal and an operation of a second processing unit configured to perform a post-processing on a signal from the first processing unit , the synchronization apparatus characterized by comprising: a counting unit configured to perform counting operation with a period that is shorter than a period of a first reference signal that governs a timing of the pre-processing in the first processing unit , and output, when it has counted a target count value that has been set, a second reference signal that governs a timing of the post-processing in the second processing unit ; a phase control unit configured to generate a control value for controlling a phase difference of the second reference signal with respect to the first reference signal to gradually approach zero in accordance with a count value of the counting unit established by the length of one period of the first reference signal and the operating period of the counting unit , the count value being a count value when the first reference signal is input to the synchronization apparatus , the count value being counted by the counting unit during one operating period of a counting period; a filter unit configured to filter the control value that has been generated by the phase control unit so as to determine a first target count value to be set in the counting unit and to set the first target count value to the target count value during normal control; and a startup control unit configured to, only at the startup, until a difference between a first count value, which is a count value of the counting unit when the first reference signal is input, and a second count value, which is a count value of the counting unit when the first reference signal is next input, is smaller than a pre-established threshold, set an initial count value to the target count value, and when the difference is smaller than the pre-established threshold, set the second count value to the target count value of the counting unit . a counting unit configured to perform counting operation with a period that is shorter than a period of a first reference signal that governs a timing of the pre-processing in the first processing unit , and output, when it has counted a target count value that has been set, a second reference signal that governs a timing of the post-processing in the second processing unit ; a phase control unit configured to generate a control value for controlling a phase difference of the second reference signal with respect to the first reference signal to gradually approach zero in accordance with a count value of the counting unit established by the length of one period of the first reference signal and the operating period of the counting unit , the count value being a count value when the first reference signal is input to the synchronization apparatus , the count value being counted by the counting unit during one operating period of a counting period; a filter unit configured to filter the control value that has been generated by the phase control unit so as to determine a first target count value to be set in the counting unit and to set the first target count value to the target count value during normal control; and a startup control unit configured to, only at the startup, until a difference between a first count value, which is a count value of the counting unit when the first reference signal is input, and a second count value, which is a count value of the counting unit when the first reference signal is next input, is smaller than a pre-established threshold, set an initial count value to the target count value, and when the difference is smaller than the pre-established threshold, set the second count value to the target count value of the counting unit . <EOS>