A test apparatus is configured such that two adjacent channels form a pair. Timing comparators determine the level of first output data fed from a DUT, respectively, timed in accordance with strobe signals, respectively. Clock envelope extractors extract envelopes of a clock, respectively. A clock recovery circuit recovers a strobe signal. A first main latch latches an output from the first timing comparator, timed by the first strobe signal. A first sub-latch latches the envelope of the clock, timed by the first strobe signal. An output from the sub-latch is supplied to a second main latch of the second channel. A signal dependent on the strobe signal is assigned an adjustable delay by a first delay circuit and is supplied to a clock terminal of the second main latch.