If leading zeros disappear when you enter a numeric value beginning with '0' into a field on Kintone, the possible causes are as follows:

"Number" fields of Kintone automatically remove leading zeros from a value when a value with two or more digits beginning with '0' is entered.
If you want to enter a numeric value beginning with '0', use one of the following fields depending on the type of the value.

• If the value is a phone number:
  • "Text" field
  • "Link" field (that has Telephone number selected for Type in the field setting)
• If the value is not a phone number:
  • "Text" field

Leading zeros of numeric values may have disappeared when your file for import was edited or saved.

To add leading zeros to field values, either edit the values one by one on the "Edit Record" screen or edit the data in the file and re-import it into the app.

Points to note when editing the file for import using Excel

When editing the file using Excel, set Text as the cell format for the column that contains numeric values beginning with '0'.

Also, when opening an exported CSV file in Excel, import the file as text data. When importing the file, select Text as the data format for the column that contains numeric values beginning with '0'.
For detailed steps, refer to When I export app data to a CSV file and open it in Excel, the values are changed.