An extragrammatical sentence is what a normal parser fails to analyze. It is important to recover it using only syntactic information although results of recovery are better if semantic factors are considered. A general algorithm for least-errors recognition, which is based only on syntactic information, was proposed by G. Lyon to deal with the extragrammaticality. We extended this algorithm to recover extragrammatical sentence into grammatical one in running text. Our robust parser with recovery mechanism -- extended general algorithm for least-errors recognition -- can be easily scaled up and modified because it utilize only syntactic information. To upgrade this robust parser we proposed heuristics through the analysis on the Penn treebank corpus. The experimental result shows 68% ¸ 77% accuracy in error recovery. 1 Introduction Extragrammatical sentences include patently ungrammatical constructions as well as utterances that may be grammatically acceptable but are beyond the synta...