This paper aims to improve the effectiveness of the grammar education of the Korean language. There are several basic questions in relation to the solution of the gap between the teacher’s grammar and the learner’s grammar. I will start with verifying the Korean grammar which teachers have in their mind and concretize the shape of the grammar required to the learners. The teaching of the grammar has been implemented without having an interest in the teacher’s grammar since teachers whose native language is Korean or who have learned the school grammar would have the grammar in which there are the contents of the grammar teaching. There should be two considerations for verifying the teacher’s grammar. One is verifying whether the teacher’s grammar is the one teachers know or the one teachers think that they know and verifying the grammar teaching based on the grammar which teachers think that they know. This means that there is a significant gap between the general school grammar and the grammar which should be taught to the learners of Korean. The other is verifying the learner’s grammar. We can use two different levels for verifying this. The first one is the comparison of the grammatical categories of the Korean grammar and of the grammar of the language that the learners know. The second one is the comparison of the contents of the grammatical categories when they have the identical categories. For solving the questions presented above, this paper deals with honorific expressions and the tense. In relation to the grammar which teachers want to teach, I point out that there is a limit of the grammatical knowledge of the teachers and they should get out of it by giving the examples of honorific expressions. For learners, they should know that they have to have the attitude of learning an entirely novel grammar since there are very rare opportunities of accordance of grammatical categories between their L1 grammar and the Korean grammar. This means that there might be some differences of delicate contents of some identical categories between their L1 grammar and that of Korean. Some examples of the tense are used for identifying this.