In order to identify the parameter of AE signal produced by pencil lead breaking with different product, relationship between mechanical property of mechanical pencil lead and AE source parameter was investigated. Dispersion of bending strength of pencil lead was first studied. Bending strength tended to increase with increasing hardness of lead. However, there was dispersion in the value of bending strength in comparison of the same hardness of leads with different products. AE parameters were next measured and identified the relationship between bending strength and AE parameter. There were no relationship between bending strength and rise time of AE sources. Rise time tended to be faster and released force was lower than the value that was conventionally used for AE analysis. Artificial AE signals were next compared by using the lead with different AE source parameters. Maximum amplitude and peak frequency was different by using different pencil lead.