Abstract: The development of this research is intended to see a character-based on authentic assessment instruments at characters and skills of students in primary school. Subjects of this study are primary school teacher primary school students seven experts for validation of assessment instruments with the following criteria mathematician teacher in primary school science teacher in primary school socials science teacher in primary school Indonesian language teacher in primary school civics teacher in primary school assessors expert and psychologists. The method used in this study is development research on the type of formative research. Its development is focused on two phases: preliminary phase and formative evaluation phase to include self evaluation, prototyping (expert reviews, one-to-one and small group) and field test. Data are collected through questionnaires and field trials. Expert validation results show that character-based on assessment instruments are valid, good and decent to see student’s character with a note it should be revised for the sub-components which having not good categorized. The results of field trials (small scale and large scale) indicates that the character-based on assessment instruments developed attitudes have good validity and have very high reliability. Thus, based on the results of expert validation and field trials, it can be concluded that the attitude of character-based on assessment instruments are valid and have very high reliability category, so the instrument is eligible to use in measuring the achievement of the student character value.